Mr. Patterson on the Cydippe Pomiformis. 95 



times on this Beroe, it is necessary to make frequent reference to its congener, the 

 Pleurobrachia Pileus, Flem., Beroe Pileus of Lamarck, Cydippe Pileus Eschs- 

 choltz, Cydippe Globuleux, BlainvlUe and Lesson, that the several points of accord- 

 ance or of difference may be enumerated as the description proceeds. Dr. Grant's 

 interesting and valuable paper " On the Nervous System of Beroe Pileus, Lam., 

 and on the Structure of its Cilia,"* has rendered that species well known to natu- 

 ralists, and furnished a standard, with which the one here recorded may with 

 facility be compared. 



In size it is from two to nine lines in length, and about a third less in breadth. 

 The general form is oval, but in some it is nearly globose, and in others flattened 

 towards the poles, and similar in shape to an orange. The difference is to be 

 attributed to a contractile power possessed by the animal, and not to any perma- 

 nent diversity in form. The body is transparent and colourless, with the excep- 

 tion of the reddish coloured intestinal vessels noticed by Dr. Fleming, and which 

 present a different aspect in different individuals. 



The eight bands to which the cilia are attached extend about three-fourths of 

 the distance from the mouth to the anus, but approach more nearly to the latter, 

 and diminish in breadth towards either extremity. In C. Pileus there are about 

 forty in each band ; in C. Pomiformis the number in some individuals amounted 

 only to fifteen, and in none which I observed did it exceed twenty-seven. Along 

 each band a cord or slight ridge extends, dividing it longitudinally into two 

 equal parts. The filaments on each band consist therefore of two parcels, which 

 in general move simultaneously, although each portion possesses a separate and 

 independent power of motion. 



Dr. Grant remarks, that the cilia of C. Pileus are the largest he had yet met 

 with in any animal, and states that " they are not single fibres, but consist of 

 several short straight transparent filaments, placed parallel to each other in a 

 single row, and connected together by the skin of the animal, like the rays sup- 

 porting the fins of a fish. Viewed with the aid of a lens, the parallel fibres 

 appeared like transparent tubes, sometimes a little detached from each other at 

 their free extremities by injury done to the connecting membrane, and at these 

 ■parts the isolated spines projected stiffly outwards. When the fins were quite 



* Trans. Zool. Soc. vol. i. p. 9. 



