kofoid: new species of dinoflagellates. 193 



hypotheca it turns to the right distally and forms a broad channel with high 

 membranous lists on either side. 



The post- and precingular plates are normal. There are four apicals and two 

 antapicals. Suture lines are marked by bands, and the plates are finely retic- 

 ulate with small subequal irregular polygons. The transverse and longitudinal 

 furrows are partially reticulated. An exceedingly variable species. 



Length, 65-155 ft; dorso- ventral diameter, 40-73 /x. 



Stations, 4691, 4730, 4732. 



Murrayella rotundata, sp. nov. 



Plate 9, Fig. 55. 



A minute spheroidal species without apical or antapical horns. 



Body rotund, spheroidal, its length 1.05 times the dorso-ventral diameter. 

 Epitheca less than the hypotheca, its altitude 0.42 of the total length and 0.44 

 of the dorso-ventral diameter, low dome-shaped, slightly flaring at girdle. 



The hypotheca is symmetrical, less rotund than the epitheca, and less flar- 

 ing at the girdle, almost hemispherical, with a minute antapical elevation a little 

 to the ventral side of the antapical pole. 



Girdle horizontal, slightly impressed, with salient ridges, forming a descend- 

 ing right spiral displaced its own width. Longitudinal furrow narrower than 

 the girdle, extending one girdle width on the hypotheca and two on the 

 epitheca. 



Length, 45 \x. ; dorso-ventral diameter, 43 /x. 



Station, 4701. 



ACANTHODINIUM, gen. nov. 



(?) Cladopyxis Stein ('83) in part. 



Body spheroidal with premedian girdle. Epitheca with apical pore, four 

 apical and eight precingular plates. Hypotheca with two antapical, six post- 

 cingular plates, and a longitudinal furrow plate of two moieties. The pre- 

 and postcingular plates and the antapicals usually bear a centrally located 

 spine, which is simple or branched distally. Thecal wall porulate. 



Acanthodinium caryophyllum, sp. nov. 



Plate 11, Fig. 67. 



Similar to A. spinosum, but with ends of spines quadripartite with hyaline 

 films connecting the divisions. Spines with one axial pore canal, occasion- 

 ally with two or three connecting or independent ones at the base. This 

 axial canal branches peripherally in the processes, which are usually four, 

 occasionally two. or three. The thecal plates are similar in number and 

 general arrangement to those of A. spinosum, and the spines show a similar 

 distribution on the plates and are subject to similar irregularities in distribu- 

 tion. The spines are longer (0.7-0.9 transdiameters at girdle) than in A. 

 spinosum, but in other respects the dimensions are nearly the same. 

 vol. l. — No. 6 13 



