Genus Bircenna, novum.
Body broad, coxæ very shallow. Antennæ sub-equal, upper without a secondary appendage. Mandibles without an appendage. Maxillipedes with well-developed plates on both basos and ischios. Gnathopoda equal, not subchelate. Last segment of pleon and its appendages rudimentary. Telson simple, not divided.
Bircenna fulvus, sp. nov. Pl. xxi., fig. 1, a to e.
Head broad, depressed in front, antennæ short, not longer than the head; both pairs of same length, slender. Peduncle of upper not distinguishable from the flagellum, first joint about as long as the second, but stouter, third shorter than the second, flagellum of about six joints, each bearing some simple auditory cilia. Peduncle of lower antennæ with four joints distinguishable, the last as long as the two preceding, flagellum of about four joints. Both antennæ with a few small setæ. Maxillipedes short, the plates on the basos and ischios reaching to the same point and nearly to the end of the maxillipede itself. Gnathopoda equal and similar, ischios as long as meros which is rounded at the end, carpus slightly longer than the meros, expanded slightly distally, propodos slightly longer than the carpus, of same width throughout, produced very slightly at its infero-distal angle, a few small setæ on inferior margin, dactylos stout, with a tooth on inner margin, not bent back upon the propodos.
First and second pereiopoda short, meros produced at antero-distal angle. Three last pairs of pereiopoda increasing in size posteriorly, basos of each much expanded. Coxæ very shallow, broader than deep. Fourth pleopoda with rami both longer than peduncle, acutely pointed, curving upwards, one nearly twice as long as the other, fifth similar but stouter, fifth segment of pleon very short, sixth apparently absent, sixth pleopoda represented by a single joint bifid at end, outer piece rounded, inner ending in a sharp point and bearing on inner margin four or five longish setæ. Telson short, triangular, with a seta on each side near the end. Length ⅛ inch. Colour, yellow.
Hab. Lyttelton Harbour.
I do not know where to place this peculiar-looking little Amphipod; it may come near to Phlias, but the species of that genius given in the Catalogue of the Amphipoda in the British Museum are not described in sufficient detail to warrant one in forming any definite conclusion as to their relationship. I have only a very few specimens.
|Fig. 1.||Apseudes latus (details). a, upper antenna x 70; b, lower antenna x 120; c, first thoracic leg x 70; d, second thoracic leg x 70; e, fifth thoracic leg x 70; f, sixth thoracic leg x 70; g, seventh thoracic leg x 70; h, end of pleon and last pleopod x 47.|
|Fig. 2.||Podocerus longimanus (details from Lyttelton specimens). a, first gnathopod of female x 70; b, second gnathopod of female x 70; c, second gnathopod of male x 30; d, end of abdomen x 70; e, extremity of last pleopod x 244.|
|Fig. 1.||Teraticum typicum x 30. a, antennæ x 120; b, first gnathopod x 56; c, palm of same x 120; d, another form of first gnathopod x 60; e, second gnathopod x 56; f, end of pleon x 120; g, telson x 120.|
|Fig. 2.||Janira longicauda (details). a, head and antennæ x 24; b, last segment of thorax, abdomen, and last pair of pleopoda x 15.|
|Fig. 3.||Stenetrium fractum (details). a, inner antenna x 60; b, outer antenna x 30; c, first gnathopod x 35; d, setæ from palm of same x 244; e, extremity of dactylos of same x 244; f, abdomen and last pleopod x 30.|
|Fig. 1.||Paranænia typica (male) x 15. a, antennæ x 24; b, mandible x 120; c, maxillipedes x 81; d, first gnathopod of male x 120; e, second gnathopod of male x 30; f, second gnathopod of female x 70; g, end of abdomen x 70; h, telson from above x 120.|
|Fig. 2.||Podocerus latipes (details). a, second gnathopod of mature female x 70; b, second gnathopod of male x 38; c, fourth pereiopod x 38; d, fifth pereiopod (for comparison) x 38.|
|Fig. 1.||Corophium lendenfeldi x 13. a, antennæ x 30; b, first gnathopod x 30; c, second gnathopod x 30; d, end of abdomen x 30; e, telson and last pleopod (from above) x 70.|
|Fig. 2.||Paranænia longimanus (details). a, second gnathopod of male x 24; b, first gnathopod of male x 120: c, end of abdomen x 30.|
|Fig. 1.||Bircenna fulva x 20. a, antennæ x 70; b, maxillipede x 150; c, first gnathopod x 70; d, telson and last two pairs of pleopoda (from above, compressed) x 120; e, end of pleon (side view) x 70.|
|Fig. 2.||Paranænia dentifera (details from a Lyttelton specimen). a, “epistoma” highly magnified; b, coxæ of first four segments of pereion x 30; c, margin of coxa of third segment of pereion x 120.|
|Fig. 3.||Panoplæa translucens (details). a, first gnathopod x 30; b, end of pleon x 15; c, telson x 38.|