The capsule gland (cps.) in Struthiolaria is a narrow, almost straight tube, about twice the length of the albumen gland, which it resembles in general structure. The lumen is primitively open along the ventral side, and is confluent with the proximal part of the ciliated oviducal groove. The right wall is attached to the mantle, while the left hangs freely, carrying along its margin a narrow flange of integument, which may be temporarily approximated to the right side to close the lumen. Through the tube so formed the penis is introduced as far as the opening of the receptaculum duct, which forms a small slit in the ventral wall of the albumen gland, just behind its junction with the capsule gland. The receptaculum (rec.) is closely applied to the inner aspect of the albumen gland, forming a large reniform sac, bulging deeply against the renal organ. Its convex dorsal edge is crested with small sacculations, while from the straight ventral margin arises anteriorly the short wide receptaculum duct. The receptaculum has a thick, circular muscle coat (60μ–70μ), and is lined with tall, clear-staining columnar epithelium, 70μ in height, with a short ciliary coat (5μ) usually obscured by the attachment of a row of eupryenic sperm heads. During the disintegration of surplus sperm, the epithelium becomes markedly glandular, with large, clear-staining goblet cells, whose secretion has apparently a digestive action on the sperms. As distinct from the Stenoglossa (Fretter, 1942), sperm ingestion does not occur.

A large amount of sperm is stored in the receptaculum at one copulatory act, and the receptaculum duct which is strongly ciliated, with well-developed muscular walls, acts as an effective sphincter, releasing backwards small amounts of sperm along the ventral groove of the albumen gland. Fertilisation doubtless occurs at the proximal end of this gland, before the egg receives its secretion layers. The eggs are rotated by the ciliated epithelium of the albumen gland, where two types of substance are secreted—a coating of albumen from the cells of the right lobe, which are finely granular, staining darkly with van Giesen's, and an admixture of mucus from the more coarsely granular cells of the left lobe, which show a strong affinity for haematoxylin. The capsule gland cells are all of the same type, staining deeply with haematoxylin, and secreting a thin, tough, mucoid capsule round each cluster of 18–24 eggs (Text Fig. 1). Each egg is at this stage 0·3 mm. in diameter, and the capsules are spherical, 2 mm. long. The capsule gland is of sufficient length to contain six or seven capsules end to end at one time, and the contents pass forward along the ciliated oviducal groove to enter the incubatory pouch in a continuous string.

The incubatory pouch is a spacious oval pocket, about 3 cm. in length, bulging deeply into the pallial cavity, and yellow in colour from the contained eggs. The aperture is an oval slit at the posterior end, through which the egg strings are transferred, by the retraction of the head and foot into the mantle cavity, so as to approximate the termination of the oviducal groove to the mantle wall. At the extrusion of the veligers the mantle margin is extended over the rim of the shell, so as to bring the pouch aperture to an external position, when the contents are expelled by wave-like muscular contractions of the pouch wall.