756 ORDER HYPOTRICHA. 



total length and so continuing to the posterior extremity; the surface of 

 both valves smooth and entire ; caudal style short and sharply pointed ; 

 pharyngeal tube long and slender, extending nearly to the centre of the 

 body; contractile vesicles two in number. Length of body 1-300". 

 HAB. Salt water. 



.ZEgyria oliva, C. & L. PL. XLII. FIGS. 43 AND 44. 



Valves of carapace ovate, but slightly compressed, smooth and entire 

 throughout ; the ventral groove wide ; caudal style short, conical, situated 

 at some little distance from the posterior extremity, and not projecting 

 beyond its border ; a dark eye-like pigment-spot developed towards the 

 anterior end ; pharyngeal tube short and straight. Length of body 1-250". 



HAB. Salt water : Norwegian coast. 



The less compressed contour of this form, compared with that of the preceding 

 species, approximates it towards the genera Phascolodon and Chlamydodon of Stein, 

 from which, however, it differs in its possession of a caudal style and in the 

 character of pharyngeal tube. The dark eye-like pigment-spot at the anterior extremity, 

 observed by its discoverers, is apparently homologous with the so-called amethystine 

 spot or globule in Professor Huxley's Dysteria armata, and with the eye-like pigment- 

 spot of Ophryoglena and many Flagellata. 



.ffigyria pusilla, C. & L. 



Valves of carapace ovate, small, narrowed anteriorly, their surface 

 smooth and even ; ventral groove somewhat widened ; caudal style conical, 

 projecting posteriorly. Length 1-600". HAB. Salt water. 



This form is briefly described by Claparede and Lachmann as being of much 

 smaller size than any other members of the genus they examined, its dimensions not 

 allowing them to ascertain the character of the pharyngeal tube. An animalcule 

 closely resembling this one in size and aspect was observed by the same writers in 

 fresh water from the river Spree, and is regarded by Stein as probably identical with 

 his Ervilia (sEgyria) fluviatilis, next described. 



.ffigyria fluviatilis, Stein sp. 



Valves of carapace ovate, compressed obliquely, truncate anteriorly ; 

 the right valve convex, ornamented by five longitudinally raised costae, the 

 left valve smooth and plane ; pharyngeal tube simple throughout, extending 

 backwards to the centre of the body ; endoplast ovate, subcentral. Length 

 of body 1-750". HAB. Fresh water. 



Stein observed examples of this species, which is described by him under the 

 title of Ervilia fluviatilis, undergoing the process of transverse fission. The speci- 

 mens examined were discovered in the clear water of a mountain stream in the 

 neighbourhood of Tharaunch. 



GENUS V. TROCHILIA, Dujardin. 



Animalcules free-swimming, ovate, encuirassed, with a convex dorsal 

 and plane ventral surface, the anterior extremity usually curved towards 



