KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 475 



Its primitive or generalized stage is indicated by the absence of recess, of 

 terminal stylet, lack of development of circular and longitudinal contractile 

 til)ers, the protractor and retractor nmscles, and of a capitate end. The ventro- 

 posterior direction is perhaps less advanced than the posterior direction seen 

 in all species of Erythropsis except E. protrudens, in which the direction of the 

 prod is the same as in Proterythropsis. 



That Ave have in this genus a connecting link between Pouchetia and Ery- 

 thropsis is further supported by the fact that the posterior end of Pouchctin, 

 in some species with the antapical loop of the svdcus twisted about that part 

 of the hypocone below the distal end of the girdle, is highly mobile in life, and, 

 as we have observed in several such species, somewhat protrusible, though it 

 never forms a permanent prod. In this connection it is well to recall the fact 

 that the i^rod of Eryfhropsis is subject to reniarkal)le changes in shape and 

 extension. 



The nucleus, with moniliform chromatin threads, is of the Pouchetia type, 

 rather than that of Eryfln-opsis, which is remarkably clear in life and often 

 has a perinuclear clear zone. 



Only one species, the type, Proterythropsis crassicaudata , is known in this 

 genus. , 



Proterythropsis crassicaudata sp. nov. 



Plate 11, figure ]23; text figure PP, 9 



Diagnosis. — A medium sized species, ellipsoidal, length 1.4 transdiameters ; 

 girdle a descending left spiral of 1.2 turns, displaced 0.8 transdiameter ; sulcus 

 of 0.3 turn ; ocellus of distrilmted ij\ic, posterior, with elongate segmented lens 

 and reddish-black pigment mass and red central core ; stout tentacle-like ventro- 

 posterior process. Length, 70/*. Pacific off La Jolla, California, July. 



Description. — Tlie body is as.yinmetrieally ovoidal, widest just below the anterior postero- 

 ventral receding face ; the outline broken by a tentacle-like process projecting ventroposteriorly. 

 The epicone equals the hypocone in length but exceeds it considerably in volume. It is broad, 

 hemispherical at the apex, with a length above the anterior flagellar pore of 0.25 and from its 

 distal extremity of 0.7 the total length of the body. The hypocone bulges out ventrally below 

 the proximal end of the girdle, is deeply grooved above the sulcus and the whole ventral face 

 recedes posterodorsally about 25° from the vertical. The antapex is then pushed dorsally. It is 

 asymmetrically hemispheroidal, without sulcal notch. 



The girdle meets the sulcus anteriorly at a point 0.25 of the total length of the body from 

 the apex. It sweeps around the body in a descending left spiral of 1.2 turns before joining the 

 sulcus again at a point 0.18 of the total length of the body from the antapex. Its total displace- 

 ment is thus 0.57 of the total length. It lies in a broad, deep trough, the margins of which bulge 

 outward in high ridges. Its width is 0.08 transdiameter, its anterior lip overhangs, and it is 

 deeply impressed. The anterior flagellar pore is located at the anterior junction of girdle and 

 sulcus and the posterior one at the distal junction. The transverse flagellum traverses only 0.2 

 of its total length, probably foreshortened as cytolysis approaches. The stout longitudinal 

 flagellum may be coiled about the prod. 



