MEDUSAE. 161 



CTENOPHOEA. 



Order : CYDIPPIDEA, Lesson. 



Family : PLEUROBEACHIIDiE, Chun, 1880. 



Pleurobrachia, Fleming, 1822. 



Pleurobrachia globosa, Moser, var. ceylonensis, nov. 



Pleurobrachia globosa, Moser (1903, p. 7, taf. i., figs. 1-4). 



The collection contains about 900 specimens, varying in size from about 2 millims. 

 up to 8 millims. in length. The largest specimen measures 8 millims. in length and 

 7 millims. in width. 



A few are preserved in formalin and these have been used for examination, as they 

 have retained their shape better than those in alcohol. The specimens in alcohol 

 suffer more or less from contraction and shrinkage. When contraction or shrinkage is 

 considerable, the position of the various organs changes so much that it would be 

 quite possible to make two or more species out of a hundred specimens. 



Locality : A few were obtained on the Cheval Paar in March and Modragam Paar 

 in November ; the great majority were from Galle Bay in June, July and August. 



Description. The body is egg-shaped, sloping towards the oral pole, and almost 

 circular in a transverse section. There are eight rows (costse) of ciliated plates, of 

 moderate length, extending over half, or a little more than half, of the meridional 

 surface, beginning and terminating at about ecpial distances from the aboral and oral 

 poles respectively. Each row contains about twenty narrow ciliated plates (combs). 

 The meridional canals are just as long as the costae. The two tentacles and their 

 sheaths lie above the level of the stomach. The base of the sheath is in the first fork of 

 the gastrovascular canals, on a level with the funnel. The sheath is like a long cone, 

 tapering from the base, and lying at an angle of about 45 degrees from the 

 perpendicular axis of the body and pointing towards the aboral end of the body. The 

 opening of the sheath on the surface of the body is just under the aboral boundary 

 line of the costae. At the bottom of the sheath is the base of the tentacle, which is 

 somewhat concave. The tentacles have lateral filaments, but no eolidiform appendages 

 were seen. The transverse canals from the funnel to the meridional canals slope 

 slightly in the aboral direction and join the meridional canals in the middle of their 

 length, slightly above the level of the funnel. The base of the tentacle lies a little 

 way from the funnel, but in a large number of specimens, owing to contraction or 

 shrinkage, the base of the tentacle is adjacent to the funnel. It has contracted back 

 on to the funnel and the top of the stomach. 



On comparing the specimens with the figures of Pleurobrachia globosa (Moser, 

 1903, taf. i., figs. 1-3), I find that they differ mainly in the length of the costse, which 



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