CUBOMEDUSAE 319 



Charyhdea appears to have a very wide geographical 

 distribution. Some of the species are usually found in deep 

 water and come to the surface only occasionally, but others 

 (C. xaymacana) are only found at the surface of shallow 

 water near the shore. The genus can be easily recognised by 

 the four-sided prismatic shape of the bell and the oral flattened 

 expansion of the base of the tentacles. The bell varies from 

 2-6 cm. in length (or height) in C. marsupialis, but a giant 

 form, C. grandis} has recently been discovered off Paumotu 

 Island which is as much as 23 cm. in height. The colour is 

 usually yellow or brown, but C. grandis is white and C. xaymacana 

 perfectly transparent. 



"Charyhdea is a strong and active swimmer, and presents a 

 very beautiful appearance in its movements through the water ; 

 the quick, vigorous pulsations contrasting sharply with the 

 sluggish contractions seen in most Scyphomedusae." It appears 

 to be a voracious feeder. " Some of the specimens taken con- 

 tained in the stomach small fish, so disproportionately large in 

 comparison with the stomach that they lay coiled up, head over- 

 lapping tail." 2 



Very little is known of the development, but it is possible 

 that Tamoya punctata, which lacks gonads, phacellae, and canals 

 in the velum, may be a young form of a species of Charyhdea. 



Fam. 2. Chirodropidae. Cubomedusae with four interradial 

 groups of tentacles. 



This family is represented by the genera Chirodropus from 

 the Atlantic and Chiropsalmus from the Indian Ocean and the 

 coast of North Carolina. 



Fam. 3. Tripedaliidae. Cubomedusae with four interradial 

 groups of three tentacles. 



The single genus and species Tripedalia cystophora has only 

 been found in shallow water off the coast of Jamaica. Specimens 

 of this species were kept for some time by Conant in an 

 aquarium, and produced a number of free -swimming planulae 

 which settled on the glass, and quickly developed into small 

 hydras with a mouth and four tentacles. The further develop- 

 ment of this sedentary stage is unfortunately not known. 



1 Agassiz and Mayer, Mem. Mus. Comp. Zool. xxvi. 3, 1902, p. 153. 

 2 F. S. Conant, Mem. Johns Hopkins Univ. iv. 1, 1898. 



