Tank Nr. 20. 



35 



MolluskS. A. Heteropods(p.Sl). Pterotrachea (fig. 97) has a 

 long proboscis and sculls itself rapidly on its back; 

 somewhat similar is the allied Carinaria (fig. 98) , less 

 transparent and with a small shell. B. Pteropods 

 (Sea-butterflies, p. 81), flap a pair of transparent wings 



(Hyalaea, fig. 99\ 



Fig. 97. Pterotrachea coronata, 

 '/2 nat. size. p. 81. 



Fig. 98. Carinaria mediterranea, 

 J /2 nat. size. p. 81. 



Fig. 99. Hyalaea 

 tridentata. p. 81. 



Besides these pelagic animals there are outside the 

 cylinders various small Octopods fp. 76), and crawling 

 Mollusks, such as *Tethys (fig. 101), as large as a hand, 

 spotted with red and brown, * Doris (fig. 100), as large 

 as a thumb, a tuft at one end, *Aeolis (fig! 102), etc. 

 Of Crustaceans various kinds of shrimps (see Tank Nr. 23). 



3* 



