KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 



50f) 



surface. The lens is composed of two flattened superposed iridescent hemispheres, the front one 

 0.3 and the rear one 0.25 transdiameter in diameter, but not deeply imbedded in the pigment 

 mass. This mass is broadly ellipsoidal, 0.35 transdiameter in length and slightly lobed. Its 

 core is of a bright coral-red color which shines through the enveloping black pigment. 



After cytolysis the ocellus (text fig. VV, 2) persists for a time. The melanosome contracts 

 and exposes a third disklike segment of the lens of the same hyaline nature as the second seg- 

 ment. It is immediately against this that the eoral-red core lies. The elements of the ocellus 

 slowly waste away by peripheral solution and fragmentation, the pigment of the melanosome 

 and the red globules of the core persisting longest. 



The large spheroidal nucleus lies in the left anterior part of the body dorsal to the ocellus. 

 It showed no beaded chromatin thread and was very hyaline, but after cytolysis it was seen to 

 have an exceedingly fine beaded chromatin network and a distinct outer perinuclear membrane 

 and inner hyaline zone. No pusule or food balls were noted. The peripheral plasma was tilled 

 shortly before cytolysis with a layer of small, uniform, rather closely packed, greenish vacuoles, 

 present everywhere except in the paraeingiilar bands. The general color was a pale glaucous 

 green. There were no chromatophores. 



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Fig. VV. Details of ocellus and tentacle of Erythropsis richardi. 1. Ocellus as revealed by cytolysis. 

 Abbreviations: irid. cap., iridescent stratified cap; dist. hy. segt., distal hyaline segjment exposed when in place 

 in the body; i)rox. hy. segt., proximal hyaline segment, imbedded in the pigment mass in the body but exposed 

 by contraction or solution of the pigment at cytolysis; core., coral-red core within the pigment; pig., black 

 pigment mass or melanosome. 2. Dorsal view of body showing retracted tentacle in capitate form. 3. Postero- 

 sinistral view exposing opening of tentacular recess and contracting tentacle. 4. Contracted tentacle in lobed 

 state seen from the dorsal side. X 500. 



Dimensions. — Length, 106-112/^; transdiameter, 85/*; diameter of nucleus, 

 40h-; of lens, 27/*; of pigment body, 30/*. 



Occurrence. — Two individuals seen, taken in the plankton 3 and 4 miles 

 off La Jolla, Juh' 26 and 27, 1917, in hauls of a No. 25 silk net from a deptli of 

 80 meters to the surface in surface temperatures of 21?4 C and 21-7 C. 



Xamed for Professor Hichard Hertwig of the University of Miinich, the 

 discoverej- of Erythropsis. The preoccupation of the specific name hertwigi 

 by a slip of the pen on the part of Jollos (1910, p. 203) precludes the use of the 

 patronymic name of this eminent protozoologist as a specific name by us in 

 Erythropsis. 



Activities. — One individual was kept under observation from 11 a.m. till 

 2 r.:\t., wlieii it tmderwent cytolysis. During this time it was feebly active, 

 moving in irregular anticlockwise spii-als in an intermittent fashion. The ten- 

 tacle was not at any time in intense activity such as that sho^Ti by E. pavillardi. 



