BIGELOW: THE CTENOPHORES. 377 



punctata Moser from the Atlantic, ochracea Agassiz and Mayer, fusi- 

 formis Agassiz and Mayer, sibogae Moser, amboinae Moser, and 

 japonica Moser from the Indo-Pacific. The Calif ornian "Mertensia 

 ovum " of Torrey is also evidently a Hormiphora. My own studies on 

 a very large series have convinced me that not all of these are good 

 species, and the necessity of identifying our own material requires 

 a preliminary revision of the genus as a whole. 



To begin with, ochracea can at once be accorded a definite status, 

 if the character by which it is distinguished, entire absence of tentilla 

 except at a very young stage (Moser, : 03), be normal. And inasmuch 

 as two collections, made several years apart and at localities as far 

 separated as off the west coast of America and the Malayan waters 

 agree in this respect, and furthermore, when Moser, who alone has 

 described adults of ochracea has also studied other members of this 

 genus, we can hardly credit the absence of tentilla to mutilation. 

 I have never seen a specimen of it myself. Apart from tentacular 

 structure, ochracea may possibly be distinguished by very long meri- 

 dional canals contrasted with short ribs; but as we shall see, this 

 character is a variable one. 



H. spatulata, according to Chun's ('98) account and figures, is 

 readily distinguished from all other Hormiphoras by the fact that the 

 tentacular sheaths diverge widely from the stomach at their oral ends, 

 and that it is only the upper (aboral) ends of the bases of the tentacles 

 which lie close against the gastric wall. And this account has recently 

 been corroborated by Moser ( : 09) for a well preserved specimen from 

 the west coast of Spain. A Ctenophore with this same characteristic, 

 and resembling spatulata likewise in general form, has been described 

 from the East coast of North America by Mayer (: 12) as Pleurobrachia 

 brunnea. According to him it is distinguished from spatulata mainly 

 by the presence of terminal knobs on the tentacles; but as Chun's 

 figure of spatulata ('88, taf. 3, fig. 3) shows a terminal knob-like 

 tentillum on one of the tentacles, it appears that the supposed differ- 

 ence in this respect is not valid. P. brunnea is almost certainly a 

 synonym of spatulata. In all the numerous Hormiphoras of the 

 "Albatross" collection (p. 38) the tentacular sheaths are in close 

 contact with the oesophagus throughout their length, so there is a 

 discontinuity in this respect, sufficient to distinguish them from 

 spatulata. Larvae of spatulata have two kinds of tentilla, ordinary 

 filiform, and large spatulate. But in the adult the latter are lost 

 (Chun, '98, taf. 3, fig. 4). 



The species which remain are less easily disposed of. The form 



