8o 



Memoirs of the Indian Museum. 



[Voi,. V, 



case. Preserved specimens may have practically any form, except that the basal 

 disk is always narrow and inconspicuous ; the aboral extremity as a whole is often 

 swollen and bladder-like. In the living animal, when the tentacles are retracted but 

 the column expanded, the anterior end is cone-shaped, the orifice above the tentacles 

 being closed by a constriction of the column-walls. 



Large specimens attain a length of 30 mm. 



The tentacles are extensile but rarely or never exceed the column in length ; 

 when contracted they are bluntly pointed and minutely annulated ; each has a ter- 

 minal pore. The disk is ample and not at all emarginate. The tentacles are arranged 



6ty. 



B. 



Fig. 3. — Phylocoetes gangeticus , sp. nov. 



A. Transverse section of column in the upper part of the stomodaeum. 



B. Transverse section of a complete and incomplete mesentery in the lower part of the 



column (more highly magnified). 

 tf. = acontium in section: cm. = circular muscle: d.m. = directive mesenteries : en. = endoderm : 

 i.m. — incomplete mesenteries : n. = nervous layer : s. = mesenterial stoma. 



round its margin. The mouth extends for about three-quarters of the breadth of 

 the disk when the latter is fully expanded, but in some preserved specimens seems 

 to be less extensive. The lips are not prominent, but there are six shallow trans- 

 verse ridges on each side of the mouth. 



The number of the tentacles is very variable ; there are usually between 50 and 

 65 ; but some as a rule are very small. These small tentacles usually occur together 

 in pairs or groups of three and are situated externally. The normal number of fully 

 developed tentacles is probably 48 or 60. 



The basal disk has the generic characters. 



The surface of the column is smooth, except for the ein elides. These, though 



