32 H. N. MOSELEY. 



cells soon in a general description, which I am preparing, of 

 the land planarians observed by me on the voyage of H.M. 

 ship Challenger. 



Schmarda, ' Neue Wirbellose Thiere,' Leipzig, W. Engel- 

 man, 1859, p. 30, appears to have seen the larvse of Mliller at 

 Belligramme. He describes it as having small villi budding 

 out from it, and refers it to Thysanozoon. 



Pteropod Larva. 



The larvse of some naked Pteropod {Gymnosomata) were 

 frequently met with on the sea surface in the Pacific Ocean. 

 The one figured Plate III, fig. 14, was taken with the surface 

 net in the South Pacific, lat. 37° 29' S., long. 8° 37' W., on 

 November 11th, 1875. It measured when moderately ex- 

 tended about 1 mm. in length. It was very lively and 

 changed its form very much ; but in the extended condi- 

 tion assumed that shown in the figure. The body was 

 covered externally by a thick transparent epidermis, marked 

 out on its outer surface into a series of polygonal areas. 

 Three zones of cilia encircled the larva, one near the an- 

 terior extremity, the other near the posterior, and the third 

 near the middle of the body. The two latter zones were 

 continuous circlets of cilia, which cilia were borne on a zone 

 of closely set ovoidal cells. The anterior zone of cilia was 

 interrupted, the cilia springing from a series of rounded 

 prominences arranged in a zone and separated by intervals 

 devoid of cilia. From this zone of prominences sprung a 

 pair of lobes (fig. 15), representing the foot. The lobes 

 appeared almost as if they were two of the prominences 

 enlarged and deprived of cilia. Beneath these lobes was an 

 elongate depression, from the centre of wliich si^rung an 

 azygos elongate tentacular-like appendage — the Zipfelformige 

 Anhang of Gegenbaur.^ The elongate depression narrowed 

 to a point inferiorly, and at its extremity was the anus 

 (fig. 15, x). 



The larva was provided with a pair of extensile lips (fig. 

 15, Plate I), from between which the globular pharynx, with 

 its radula sac already containing rudiments of teeth, could 

 be protruded. The pharynx was provided with strong re- 

 tractor muscles. A straight narrow oesophagus led down 

 the axis of the body to the mass of light brown-coloured 

 cells representing the digestive tract. A short rectum led 

 obliquely up from below to the anus. A mass of large 

 highly refractile transparent cells surrounded the mass of 



' Gegenbaur, 'Pteropoden und Heteropodeu.' Leipzig, 1855, taf. iv, 

 figs. 7 auu 8, &c. 



