76 



Buccal appendages: two pair of buccal cones (fig. 131 — 132). 

 Labial tentacles: small, situatecl about as much clorsally as ventrally. 

 Radula: the formula is 8.0.8 (fig. 135). 



Length: the pigmented specimen measures 6 mm., the two other specimens are 5 mm. 

 Colour: the pigmented specimen is yellow; the other specimens are greyisli (spirit- 

 preservation). 



Observation: I have tried to give a sufhcient description of the Siboga-specimens, 

 in which I could not observe any specific difference from the Nofodraiichaea inopinata of 

 Pelseneer. This species was found by the Challenger, east of Japan (35°29'N., 179° 50' W.) 

 and afterwards it has been recorded ') from Port Jackson Heads, New South Wales. 



To the Notobranchaeidae, and probably to Notobranchaca a curious larva must be 

 referred (PI. V, figs. 136 — 138). This larva was found at Stat. 36 (7°38'S., 11 7° 31' E.). 



The length is only 2 mm. A great many glands are scattered all over the body, but 

 at the place, where the three crests of the ])Osterior gill are situated in adult specimens, the 

 glands are very closely grouped together, and this accumulation also occurs at the posterior 

 extremity (fïg. 138). The two posterior ciliated rings are still discernible as thin white lines. 

 The whole body is more pointed, the visceral sac does not occupy the posterior third of the 

 body. The fins are rounded and broad ■, the anterior lobes of the foot are free for half their 

 length, and the posterior lobe is pointed — quite as in Notobranchaea inopinata. The neck is 

 shorter and broader (perhaps due to stronger contraction). The nuchal tentacles are placed 

 far back. The proboscis is somewhat evaginated and shows also two shallow hook-sacs, with 

 bunches of hooks By clearing the specimen in glycerin, I could observe two pair ot buccal 

 cones. The skin is without pigment and of a grey colour (alcoholic preservation). 



A n a t o m i c a 1 R e m a r k s. 



The anatomy of A^otobranchaca has never been studied until now. Though I could not 

 push my researches so far as to give a complete anatomical description, I shall try to indicate 

 a few things which I have observed. 



The external appearance of the animal has been already described. 



The proboscis possesses false "lips" as in Clionc, the buccal appendages being therefore 

 inserted around the secundary mouth. The cephaloconi number two pairs. Their internal 

 structure I could unfortunately not make out, as the dissected specimens did not clearly show 

 delicate histological details. I could only see on transverse sections : (ij a micldle muscular 

 region, consisting of an exterior layer with annular fibres and an interior one with longitudinal 

 fibres, (2) an internal region formed of glandular cells, while the (3) epithelial investment 

 nothwithstanding I took much care to investigate it, has remained indistinct. Probably, the 



l) Brazier, Australian Museum Catalogue (1892), n" 15, Pit. II, Pteiüpoda, p. 42. 



