86 



F ins: these locomotory organs are also a liule deviating from the usual type. They 

 are narrow at their base, enlarged at their distal extremitj-, which is membraneous, especially 

 in the middle, and exhibits a sinuosity (fig. 153,/). 



Digestive tract: The mouth, bordered by false "lips", opens immediately behind 

 (dorsally to) the anterior lobes of the foot. At the .sides of the lips the buccal appendages are 

 inserted. The.se appendages are long, flattened and very contractible. I have tried to examine 

 their histological structure, but as neither transverse or longitudinal .sections (10 or 5 rj.u..), 

 nor staining in toto and mounting, has given me .sufficient results, I think it better to pass over 

 this structure in silence, rather than to speak of something, about which I could not obtain 

 absolute certainty as yet. 



A protrusile proboscis is quite absent. The oesophagus has a narrow lumen, as its 

 walls are laid in large folds. — The radula is strongly developed. Its formula i . i . i agrees 

 with what is found in the Thecosomata, but Boas and Pelseneer have clearly jjointed out, 

 that this conformitv in the number of teeth is cjuite accidental. Be.sides, the form of the teeth 

 (fior. 155) is quite different from that of the Theco.somata. The median tooth has no denticles; 

 each lateral tooth jDos.sesses a broad ba.se and a slender ]joint, which is turned upwards. There 

 are sixteen or .seventeen transverse series in the radula. — Immediately in front of it, the jaws 

 are situated, each of which consists of two or three rows of horny plates, the free margin of 

 which is saw-shaped (fig. 156). The anterior plates are stronger than the posterior ones. The 

 jaws themselves unite neither dorsally nor ventrally. — Hook-sacs do not exist here. — Salivary 

 glands are the same as in all Gymnosomata and without real efferent duct. — The oesophagus 

 opens into the stomach at its left anterior corner; the structure of this stomach does not offer 

 special discussion. The intestine arises at the ventral side and runs straight on to the anus, 

 which lies beneath the posterior lobe of the foot, and nearly in the median line, though 

 somewhat to the right. Souleyet says that the intestine "decrit t]uelques inflexions autour de la 

 poche .stomacale"; I have never seen this. 



Musculature: In the reticulated connective tissue between the skin and the visceral 

 mass, three flattened muscle-bands attach this visceral mass to the body-wall. They are inserted 

 in the region of the neck, while distally they divide into several branches, which are strongly 

 attached to the skin. Two of the muscles are dorso-lateral, one on each side of the body. 

 The third is ventral and median. 



Generative organs: the gonad is situated posteriorly, and sometimes a little ventrally, 

 to the stomach. The efferent duct issues quite donsally, then passes to the left and ventrally 

 (without exhibiting perceptible swellings in its course) and opens in the usual position, beneath 

 the distal margin of the right fin. As the stomach occupies the left portion of the visceral 

 mass, the genital duct is situated at the right side of the stomach ; it crosses the rectum at 

 its dorsal side. The accessory genital glands and the receptaculum seminis are situated in the 

 usual position, but I could not observe a separate muciparous and an albuminiparous gland. 

 The accessory genital glands have been already recorded and figured by Souleyet "). Speaking 



1) \'oyage dc la Honite, vol. II, p. 246. 



2) Voy.age de la Bonite, vol. II, p. 24S, pi. XV, lig. 4. 



