168 PERCY SLADEN TRUST EXPEDITION 



B. PSEUDOTHECOSOMATA. 



Cymbuliidae. 



Cymbulia Pe"ron et Lesueur. 



20. Cymbulia sp. 



Stat. B (3), C (47), F (4), N. of Chagos Archipelago ; L (1), W. of Chagos Archipelago ; 

 d (2), Mauritius; 1 (l), Nazareth Bank; p (l), q (2), Farquhar ; x (l), Providence; 

 aa (2), bb (2), N. of Providence; nn (1), Amirante Group. 



At many stations representatives of the genus Cymbulia, apparently mostly young 

 forms, were obtained. They all possessed in a more or less advanced stage of growth 

 a ventral lobe to the fin, and the larger specimens seemed to agree in all essential features 

 with Cymbulia sibogce Tesch, which has already been recorded by Meisenheimer* from the 

 Chagos Archipelago and from the Seychelles. Unfortunately none of my specimens 

 possessed a concha ; a clear determination was not therefore possible. 



Desmopterus Chun. 



21. Desmopterus papilio (Chun). 



Stat. A (10), B (3), F (4), N. of Chagos Archipelago; Q (l), Chagos Archipelago; 

 x (1), Providence; kk (2), Amirante Group. 



The specimens had lost all pigment ; the tentacular process on the fins was always 

 more or less broken off. 



22. Desmopterus gardineri, n. sp. (Plate 12, figs. 1, 2.) 

 Stat. B (1), N. of Chagos Archipelago. 



The general form of the body is about the same as in D. papilio, on the whole 

 cylindrical ; proximally, however, it becomes gradually more slender and forms a short 

 proboscis, almost perpendicular to the axis of the trunk : distally, it bears a ventral groove, 

 composed of large glandular cells. The very thin, transparent integument is provided with 

 a great many unicellular, but rather large, roundish glands. Similar glands have also been 

 described by Meisenheimerf in D. papilio, though they are here much smaller. The 

 musculature of the fins forms the most prominent character of the new species ; this 

 musculature is composed of rather broad bands, all distinctly separated, and running 

 in two main directions, the one at right angles to the other. Distally a few bands only of 

 the horizontal system, after passing into the inner ventral lobe of the fin, take an opposite 

 direction and form part of the vertical bands. The whole system is very much like that of 

 D. papilio except for the much broader and clearly separated bands ; there accordingly 

 exists in the musculature of the fins a similar difference like that of Cymbulia compared 

 with Corolla. The knob-like, small agglomerations of glands, described by Meisenheimer J 

 on the fins of D. papilio I also found in D. gardineri. 



The only specimen obtained was in the $ stage, as is shown by the presence of a 

 distinct penis, invaginated at the right side of the head (fig. 2, <p). The gonad (fig. 1, gon) 



* Pteropoden der deutschen Tiefsee-Expedition, p. 38. t I.e. p. 209, PI. xiv. tigs. 8, 13. 



% I.e. p. 209, PI. xiv. fig. C. 



