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Volume 48, 1915
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Art. XXXVII.—On the Gonoducts of the Porcupine-fish (Dicotylichthys jaculiferus Cuvier).

[Read before the Wellington Philosophical Society, 22nd September, 1915.]

In the Teleost fishes generally the gonoducts, when distinct ducts are developed, either open together to the exterior, or both open into the base of the ureters or of the combined urinary duct I have been unable to find a recorded case in which the two gonoducts discharge separately to the exterior, the condition that exists in Dicotylichtys jaculiferus so far as the male is concerned

The mesonephridia are large, and in each the ureter arises from the posterior end, toward the ventral aspect The two ureters converge as they run backwards, and about 4 cm before they unite they become closely bound together by connective tissue (removed in the preparation figured). Their union forms the urinary bladder, which discharges by a median opening into a shallow urino-genital sinus situated just behind the anus

The testes are large, and their ducts are very short indeed Each has its own opening, difficult to distinguish, into the urino-genital sinus The two openings are slightly in front (ventrad) of the urinary opening, and

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Fig 1.—Just after emerging from egg
Fig 2—Age seven days

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Fig 1— Age twenty-six days
Fig 2.—Age not known. This is one of the numerous young specimens found in rock-pools in October.

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are situated one on either side of it. By opening the testes a probe can be passed along the duct, and I have verified the observation by drawing a thread through each duct.

In the female the ovisacs have very short oviducts of considerable width, which open separately at the very mouth of the urinary opening.

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Dicotylichthys jaculiferus : Male urinary and genital organs dissected from dorsal aspect 1 left kidney; 2, left ureter; 3, opening of left ureter into urinary bladder; 4, urinary bladder, part of dorsal wall removed; 5, opening of urinary bladder into urino-genital sinus; 6, left testis, part of posterior end removed; 7, opening of left sperm-duct into urino-genital sinus; 8, opening of right sperm-duct into urino-genital sinus; 9, anus.

For several of the specimens of Dicotylichthys examined I am indebted to Professor Prince, of Ontario, and Mr. T. Anderton, of the Portobello Marine Fish-hatchery, the specimens having been obtained during Professor Prince's investigations on the New Zealand coast.