478 MEMOIRS OF THE XTNIVERSITY OF CALIFORNIA 



directed tentacle or prod which in several species attains a length twice that 

 of the body and is subject to incessant rhythmical contractions. It may or may 

 not have a capitate end and a terminal stylet. An attachment area may be 

 found at the distal end of the girdle. The form is somewhat rigid and the 

 surface almost differentiated into a distinct pellicle, mottled by vacuoles as 

 cytolysis apiDroaches. Ko striae are present. Anterior pusule attached to the 

 anterior flagellar pore and another to the tentacular recess. Posterior longi- 

 tudinal flagellum jjrobably present in addition to tentacle, but evanescent or 

 easily- lost. A single ellipsoidal nucleus present. The chi'omatin network not 

 distinct in life. Perimiclear zone with A-acuoles and envelope are sometimes 

 present. No chromatophores. Pigment usually confined to the ocellus, dis- 

 tributed as a network of scarlet in one species. Plasma homogenous and trans- 

 lucent. Nutrition evidently holozoic. Binary fission not observed. Autotomy 

 of tentacle and cytolysis occur on slight stimulus. 



All small, marine species 48-130m in length. Ten species known from warm 

 temperate and tropical seas. 



Desceiption 



The form of the body in Erythropsis is highly specialized, due to the invasion 

 of the h}T^)ocone by the ventral recess (fig. RR, tent, rec), the foreshortening 

 of the epicone, and its apical flattening. This form appears to have been 

 brought aljout by a reversion from a condition of greater torsion, so that the 

 sulcus, instead of having a considerable obliquity in the intercingular area, as 

 in Poiichetia, hag, in Erytht-opsis, an almost straight course in this section, and 

 the distal end of the girdle in compensation is deflected abruptly posteriorly 

 in the distal 0.15 or so of its course. The result of this reduction in torsion 

 is api^areut in the almost horizontal course of most of the girdle, its marked 

 distal deflection, and the straight intercingidar sidcus. Accompanying these 

 modifications of the girdle and sulcus, and possibly the prime cause of their 

 origin, is the considerable increase in relative size of the ocellus and its anterior 

 location. The ventral recess is a deep excavation opening ventroposteriorly 

 and sheltering the basal end of the prod. Ventrally it is the continuation of 

 the sulcus and posteriorly it is terminal and even axial. It also contains the 

 opening of the posterior pusule, the posterior flagellar pore, and the jDosterior 

 flagellum. It is thus the deeply recessed posterior end of the sulcus. 



The ocellus of Erythropsis is in all cases premedian, often far anterior, 

 usually protuberant, directed anteriorly, never horizontally or posteriorly. It 

 is also relatively very much larger than in Pouchetia. It is present in both the 

 diffuse ty]")e (subgenus PolyopsidcUa) and the integrated subgenus Erythropsis. 

 The integrated forms attain a high degree of specialization, as in E. corniita, 

 E. protrudens, and E. pavillardi. It is a matter of note, as indicating that the 

 whole organism shares this specialization, that it is in these same species that 

 the paracingular lines and the prod are also highly developed. The presence 



