EASTERN CAyADIAN PLANKTON 93 



VIII. 



Eastern Canadian Plankton.— The Distribution of Float- 

 ing Tunicates (Thaliacea) obtained during the 

 Canadian Fisheries Expedition, 

 1914-1915. 



BY 



A. G. HuxTSMAN, B.A., M.B., F.R.S.C, 

 Biologist to the Biological Board of Canada. 



Comparatively few individuals of this group vpere obtained on the expedition, 

 forty-five in all, belonging to five different species. The nomenclature is that of Ihle 

 (1912) for the Desmomyaria and that of Neumann (1913) for the Cyclomyaria. 



Key to the Species. 



Ai. Muscles of body forming usually incomplete rings. A single pair of large 

 branchial stigmata. ^ Salpidae. 



Alimentary canal coiled to form a nucleus, or, if not, muscles of the body very 

 numerous. Salpa. 



Bi. Muscles not in groups. 



Cj. Muscle bands, more than six. 18 to 22 more or less interrupted muscle 

 bands. A pair of long posterior processes or spines. 



S. vagina solitar. 

 C2. Muscle bands, not more than six. 



Di. Muscle bands all incomplete above. Five broad and one narrow 

 muscle bands. S. zonaria solitar. 



D2. Muscle bands not all incomplete above. Five muscle bands between 

 ganglion and atrial opening, the first incomplete above. 



8. zonaria gregat. 



Bj. Muscles arranged in groups. 



El. An anterior group of three. Muscles incomplete above. Anterior three 

 muscle bands approaching each other, more or less interrupted. Two 

 solitary bands behind. 8. vagina gregat. 



Eg. An anterior group of three. Muscles not incomplete above. 



Fi. Not more than six muscle bands. An anterior group of three and 

 a posterior group of two muscle bands, widely separated. 



8. democratica. 



G^. Test with posterior spines. 8. democratica solitar, 



Gg. Test without posterior spines. 8. democratica gregat, 



F2. More than six muscle bands. An anterior group of three, a posterior 

 group of two, and between these four solitary muscle bands. 



8. fusiformis solitar. 



