422 



CTENOPHORA 



movements. Very little is known at present concerning many 

 details of the internal anatomy, but there is one point of con- 

 siderable theoretical interest namely, the presence of definite 

 male genital ducts. 



Three of Dr. Willey's specimens were mottled with a green 

 pigment, whereas his fourth specimen and KorotnefFs only speci- 

 men were mottled with a red pigment. It has yet to be deter- 

 mined whether the differences which have been observed in the 

 individual specimens are of specific value. 



Fam. 2. Coeloplanidae. Coeloplana was originally discovered 

 by Kowalevsky in the Eed Sea, but has recently been found by 

 Abbott l on the coast of Japan. 



The Japanese species are found principally on encrusting 

 Algae, Zostera, Melobesia, etc., which they resemble very closely 



in colour. The Eed Sea species is, 

 according to Kowalevsky, ciliated 

 all over, but the Japanese species 

 are ciliated only on the ventral 

 x^ " surface. As in Ctenoplana, the 



^ body of Coeloplana is a flattened 



disc with a notch at each end of 

 the tentacular axis, when creeping ; 

 but Coeloplana does not swim, nor 

 at any time does it assume a 

 helmet -shape. The tentacles are 

 very long and of a chalky-white 

 colour. They can be retracted into 

 j tentacle-sheaths. When the animal 



Fl^.iss. Coeloplana mitsukurii, float- [ s excited it throws out the whole 



inor a t the surface of the sea with , , , . , , ,., , 



the dorsal side downwards. T, T, tentacle in a cloud ot white iila- 



the tentacles expanded. (After me ntS, "and to Watch it at Slich 



a time, shooting out and retracting 

 the tentacles, moving along the side of the aquarium like a 

 battleship in action is truly a remarkable spectacle." 2 On the 

 dorsal side of the body there is a series of processes which are 

 called the dorsal tentacles. The statolith is very small, and 

 is not surrounded by sensory processes as it is in Ctenoplana. 

 There are no ctenophoral plates. The colours of the Japanese 



1 Annot. Zoolog. Japon. iv. pt. iv. 1902, p. 103. 

 2 Abbott, I.e. p. 106. 





