462 Mr. E. T. Browne on the Medusce 



solely for that reason that I have refrained from joining all 

 the above-mentioned species under one name. 



The normal number of cordyli between every two tentacles 

 in the British form is one, and one is also found in the Medi- 

 terranean form. Laodice ulothrix, according to Hgeckel's 

 figure, has two cordyli, but Mayer has described specimens 

 with one cordylus between every two tentacles. Laodice 

 calcarata, according to Agassiz, has one or two cordyli 

 between the tentacles, but Brooks mentions specimens with 

 only one. It is evident that there is one cordylus between 

 every two tentacles and that some specimens may have one 

 or two ; but there is no evidence that any of the North- 

 Atlantic species have always two cordyli between every two 

 tentacles. The same is the case with the cirri, either one or 

 two between every two tentacles. Allowances must be made 

 for development and also for breakage in preserved specimens. 

 Brooks records a variety of Laodice without cirri from 

 the Bahamas, but Mayer records specimens with cirri from 

 the same region. 



The ocelli are certainly very variable in number. In some 

 specimens every tentacle is provided with an ocellus, whereas 

 in others comparatively only a few tentacles have ocelli. 

 Gegenbaur figures an ocellus at the base of the cordylus in 

 L. medtterra7iea, and Brooks also mentions a variety with 

 ocelli in the same position from the Bahamas. The ocellus 

 belongs really to a tentacular bulb in an arrested state of 

 development, upon which the cordylus is situated. I have 

 found that the British form of Laodice has a very variable 

 number of irregularly distributed ocelli, so that they are of 

 little use for a specific character. 



The length of the gonads along the radial canals is useless 

 for a specific character, as the length depends upon growth. 



There is certainly a difference in colour, but colour unfor- 

 tunately usually disappears after preservation, and, moreover, 

 the descriptions do not always state whether the colour 

 described is that of the living medusa or of a specimen in 

 alcohol or some other fluid. I have seen large living specimens 

 of the British form which were quite colourless, and other 

 specimens from the same locality with pink gonads. There 

 is, however, a tendency for the European forms to have 

 pinkish gonads and the American forms to have dark yellowish 

 to brown gonads. Mayer describes L. ulothrix from the 

 Bahamas as being dull pink, brownish, or greenish white, so 

 that it appears to me that colour is of little use as a specific 

 character. 



On bringing together the characters of the three species 



