460 ORDER CILIO-FLAGELLATA. 



a projecting claw-like point ; no dorsal crest ; the posterior segment 

 rudimentary, consisting of a very narrow concave plate ; ventral plates 

 strengthened by one or two linear thickenings ; surface of cuirass finely 

 shagreened. Length 1-550". 



HAB. Salt water : Norwegian coast (Claparede & Lachmann). 



Dinophysis rotundata, C. & L. 



Body inflated, compressed, transverse annular furrow set further forward 

 than in D. acuminata, the posterior segment being in consequence of pro- 

 portionally larger size, its margin convex ; surface of cuirass coarsely 

 shagreened ; no keel-like dorsal crest ; ventral plates with two transverse 

 linear thickenings. Length 1-500". HAB. Norwegian coast (C. & L.). 



Dinophysis ovata, C. & L. PL. XXV. FIG. 43^. 



Body ovate, compressed, two closely approximated spine-like processes 

 developed at the anterior extremity, the posterior segment convex, cap- 

 shaped ; surface of the cuirass finely shagreened ; no keel-like dorsal crest ; 

 ventral plates extending along two-thirds of the ventral border, strengthened 

 by two linear thickenings. Length 1-625". 



HAB. Salt water : Norwegian coast (C. & L.). 



Dinophysis Isevis, C. & L. 



Body suborbicular, compressed, surface of cuirass entirely smooth ; 

 ventral plates produced throughout almost the entire length of the ventral 

 border, strengthened with three linear thickenings ; posterior segment con- 

 spicuously developed, its margin slightly convex ; no dorsal crest. Length 

 1-400". HAB. Salt water : Norwegian coast (C. & L.). 



Dinophysis arctica, Mereschk. 



Body broadly flask-shaped, inflated and widest anteriorly, contracted 

 posteriorly, scarcely one and a half times as long as broad ; ventral crest 

 largely developed, angular, and obliquely truncate anteriorly, traversed by 

 three transverse lines ; surface of cuirass finely shagreened throughout. 

 Length 1-600". HAB. Salt water: White Sea (Mereschkowsky). 



This species closely approaches D. lavis, but is to be distinguished from that 

 form by its smaller size, the shagreened character of the cuirass, and by the 

 diverse contour of the ventral plates. 



Dinophysis caudata, S. K. 



Body suburceolate, the region behind the transverse annular furrow con- 

 sisting of an inflated, urceolate, basal portion and an abruptly narrowed, 

 subcylindrical, ventrally curved, anterior prolongation ; a smooth, narrow 

 ridge produced along the dorsal border of the inflated portion of the posterior 

 segment, and on the opposite or ventral margin of the same region two 

 conspicuously developed fin-like ventral plates ; ventral plates angular, 



