4 JOHNS HOPKINS UNIVERSITY MORPHOLOGICAL MONOGRAPHS. 



Species : Charybdea Xaymacana (Fig. 1). 



Bell a four-sided pyramid with the corners more rounded than 

 angular, yet not so rounded as to make the umbrella bell-shaped. The 

 sides of the pyramid parallel in the lower two-thirds of the bell, in the 

 upper third curving inward to form the truncation ; near the top a slight 

 horizontal constriction. Stomach flat and shallow. Proboscis with four 

 oral lobes, hanging down in bell cavity a distance of between one-third 

 and one-half the height of bell ; very sensitive and contractile, so that it 

 can be inverted into the stomach. The four phacelli epaulette-shaped, 

 springing from a single stalk. Distance of the sensory clubs from the 

 bell margin one-seventh or one-eighth the height of bell. Velarium in 

 breadth about one-seventh the diameter of the bell at its margin. Four 

 velar canals in each quadrant ; each canal forked at the ends, at times 

 with more than two branches. Pedalia flat, scalpel-shaped, between one- 

 third and one-half as long as the height of bell. The four tentacles, when 

 extended, at least eight times longer than the bell. Sexes separate. 

 Height of bell, 18-23 mm.; breadth, about 15 mm. (individuals with 

 mature reproductive elements) ; without pigment. Found at Port Hen- 

 derson, Kingston Harbor, Jamaica. 



As may be seen from the above, C. Xaymacana differs only a little 

 from the C. marsupialis of the Mediterranean. Glaus mentions in the 

 latter a more or less well defined asymmetry of the bell, which he 

 connects with a supposed occasional attachment by the proboscis to algae. 

 In C. Xaymacana I never noticed but that the bell was perfectly sym- 

 metrical. C. Xaymacana is about two-thirds the size given by Glaus for 

 his examples of C. marsupialis, which were not then sexually mature. 

 It has 16 velar canals instead of 24 (32), as given by Haeckel, or 24 as 

 figured by Glaus. Difference in size and in number of velar canals are 

 essentially the characteristics upon which Haeckel founded his Chal- 

 lenger species, C. Murrayana. 



Family II : CHIRODROPID,E (Haeckel, 1877). 



Cubomedusas with four interradial groups of tentacles ; with sixteen 

 marginal pockets in the marginal lobes of the velarium, and with eight 

 pocket arms, belonging to the exumbrella, in the four stomach pockets. 



This family is represented in American waters by a species of 

 Chiropsalmus, identified by H. V. Wilson as C. quadrumanus, found at 

 Beaufort, North Carolina. 



