75+ ORDER HYPO TRIG HA . 



long inhabited a small marine aquarium. A reproduction of the illustrations accom- 

 panj-ing the original description of this relatively complex t)'pe will be found at 

 PI. XLII. Figs. 27-30. 



Genus III. CYPRIDIUM, S. K. 

 (Cypris ; Mf/w, like.) 

 Animalcules free-swimming, encuirassed, elongate ovate or oblong, 

 bilaterally compressed ; the ventral surface ciliated, narrow and groove-like ; 

 the right and left valves of the carapace coalescing with one another at the 

 posterior end only of the dorsal border ; a tail-like spine or style projecting 

 from the posterior extremity of the ventral groove; pharjmgeal armature 

 consisting of a simple, cylindrical horny tube. Mostly inhabiting salt 

 water. 



Tiie author has conferred this new generic title upon various species referred by 

 Claparede and Lachmann* to the genus Dysteria, from which, how-e\er, they are to be 

 distinguished by the simple tubular character of the phar)-ngeal armature. The 

 superficial resemblance of tliese bivalved Infusoria to certain Ostracodous Crustacea, 

 such as Cypris, has suggested the generic name adopted. 



Cypridium lanceolatum, C. & L. sp. Pl. XLII. Figs. 31-33. 



Valves of carapace ovate, much narrower posteriorly, the left one having 



a raised, arcuate, longitudinal costa, extending the whole length of and 



adjacent to the dorsal region, emarginate at its anterior border ; the right 



valve perfectly smooth and rounded ; pharyngeal tube slender, straight, 



developed backwards to the centre of the body ; the posterior or caudal style 



lanceolate, equal in length to nearly one-half the diameter of the carapace ; 



the cilia longer and more thickly developed at the anterior extremity ; 



contractile vesicles two in number, situated near the ventral surface ; 



endoplast single, spherical, subcentral. Length of body, 1-350". 



Hab. — Salt water : Norwegian coast (C. & L.). 



This species is identical with the Dysteria lanceolata of Claparede and 

 Lachmann. 



Cypridium spinigerum, C. & L. sp. Pl. XLII. Fig. 34. 

 Valves of carapace elliptical, the more convex valve having a singL 

 longitudinal sulcus and two spinous prominences on the dorsal border ; the 

 opposite one plane, smooth, and entire ; caudal style long and slender. 

 Length of body 1-400". Hab. — Salt water. 



A very imperfect description of this genus is given by Claparede under the title 

 of Dysteria spinigera, and in which it is left undetermined whether it is the right or 

 left valve that is sulcated and bears the spinous processes, while no details are 

 recorded concerning the pharyngeal tube, nor as to the dimensions of the animalcule. 

 It is stated, however, to be smaller than the species last described, C. larueolatum. 



Cypridium aculeatum, C. & L. sp. 

 Valves of carapace elliptical, subequal ; the right valve the more convex, 

 having a marginal dorsal crest which terminates anteriorly and posteriorly 



* ' Etudes sui les Infusoires.' 1858-60. 



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