77 



structure of the cones will not difter greatly from that of the cephaloconi in Clione, as described 

 by Pelseneer ^). 



The radula is strongly developed, without median tooth. The hook-sacs are short; each 

 hook (one cell) bears a large nucleus at its base, while the horny layer is only found at the 

 free periphery of the tapering cell. 



Very remarkable are some bladder-like organs around the oesophagus, and reaching as 

 far as the stomach. Though these Ijladders open sometimes in each other, a communication 

 with the digestrive tract or with any other organ does not exist at all. They are therefore 

 similar to the "Schlundblasen", noticed by Meise.vheimer '") in Pferoceanis, and about which an 

 extensive description will soon be published. 



The structure of these sacs is the following (PI. V, fig. 139): a layer of epithelial 

 cells is found peripherically {a) with very flat, small nuclei, and at the inside of this layer, a 

 region of glandular cells [d) with large nuclei and with prolongations into a reticulated network 

 of branched cells [c) with very small nuclei. The inner part of the sac is probably filled with 

 secretion of the glands. It may be noted, that the epithelial layer at the outside does not 

 always occur. 



I have seen no salivary glands. 



As to the rest of the digestive tract, I have observed no differences from that of other 

 Gymnosomata. The ciliated villi of the oesophagus end into the stomach, which is rather 

 wide and wholly unarmed. The intestine is short and goes directly upwards, opening beneath 

 the right fin. 



The shape of the generative organs too is quite similar to that of other Gymnosomata 

 (fig. 140). The gonad (g) is rounded and occupies the posterior part of the visceral mass. 

 This gland consists of the .same hermaphrodite lobules as in the preceding families. A 

 thin efferent duct [d), soon enlarging in its course, arises from the gonad and reaches the 

 accessory genital glands. The albuminiparous [6) and muciparous glands {a) have a different 

 aspect on their surface, the plicae of the former being smaller and more numerous. A "vagina" 

 (Gegenbaur) proceeds from the dorsal surface {z') of the accessory genital glands. The penis, 

 coiled up in the head cavity, exhibits on its surface (when invaginated) at the right side, a 

 broad, winding band, consisting of very high epithelial cells (fig. 141). 



The disposition of the ganglia in the central nervous system scarcely presents anything 

 remarkable, as far as I could perceive. The cerebral ganglia are closely placed together above 

 the oesophagus, but show a distinct commissure. The ganglia below the oesophagus are 

 arranged in the same manner as in the Pneumonodermatidae; the visceral ganglia too are 

 asymmetrical, the left being the larger. From this ganglion issue two nerves, the right visceral 

 eanelion is destitute of such nerves. 



i) The cephalic appendages of the flymnosomatous Pteropoda and especially of Clione. (Tuartevly Journal Micr. Sc, vol. XXV 

 (1885). p. 491 — 509, pi. XXXV. 



2) Ubei- eine neue Familie der gyninosomen Pteiopodeu aus deni Material der Deutschen Tiefsee-Expedilion (PtcroceanidenJ, 

 Zool. .\nz., Jahrg. XXVI, p. 96. 



