KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 493 



July 23 and 27 and August 20, 1917, in surface temperatures of about 20?2 C, 

 21?4 C. and 22° 0. 



Schiitt (1895) figures it, presumably from the Bay of Naples or from the 

 Atlantic. 



AcTrv'TTiES. — The individual under observation was brought to the labora- 

 tory at 10 A.M. and was first captured in the large jar of fresh sea water at 

 4 P.M. and placed under the cover glass. It remained active for only a few 

 moments, keeping the prod in ra])id, regular contractions several times per 

 second and moving spasmodically in an anticlockwise circle of short radius. 

 The prod soon began to slough off, its contractions to become irregular, and the 

 outward thrust to grow shorter and shorter, until within an hour all movement 

 ceased and cytolysis ensued. 



Synonymy. — Figured as Pouchetia cornuta by Schiitt (1896, pi. 26, figs. 

 96,-3), who failed to recognize its relationship to Hertwig's Erijthropsis. The 

 fact that he does not list Hertwig's (1884) paper in his bibliogra])hy or recog- 

 nize the genus in his PfJunzenfawilien (1896) indicates that he did not recognize 

 Erijthrupsis as a dinoflagellate. His figure and text alike show that he did 

 not recognize the tentacle or prod. His drawing was evidently made from a 

 moribund specimen. 



Comparisons. — Our individual appears to be identical with the form figured 

 by Schiitt (1895, pi. 26, fig. 96) as Pouchetia cornuta. His magnification gives 

 a length of 105m for his smaller figure and 120|t for the larger, at the same 

 magnification. However, the magnification is not given for the larger figure, 

 though both are said to have been made from the same living cell. The tentacle 

 is prol)al)ly represented by the rounded knob from whose base the longitudinal 

 flagelhun springs. The outline, girdle, sulcus, and paracingular lines are strik- 

 ingly similar in his figures and ours, although he did not record the intercing- 

 ular part of the sulcus, and vindoubtedly j)ortrays incorrectly the proximal end 

 of the girdle as ascending to the tip of the apical horn. This horn is also figured 

 as deflected to the right, whereas we record it as deflected to the left. This may 

 be due to its mobility or to inaccuracy of record on the part of one of us. In 

 view of the difficulties in securing an accurate interpretation of this obscure 

 region, these discrepancies may be regarded as negligible, in so far as they 

 affect the question of specific identity. 



This species is close to E. agilis Hertwig, but differs in shape of the body 

 and lack of broadly truncate antapex. The ocellus is of the same simple 

 type, but the melanosome is extended longitudinally instead of transversely, 

 as in E. (igiUs, and the apical horn is more fully developed. Tlie body is 

 smaller and far less rotund than in E. cochlea (Schiitt) and larger and stouter 

 than in E. paviUardi, and its prod is of a different type, having a terminal stylet. 

 The posterior position of the prod differentiates it from E. extrudens, and its 

 very large size and long prod, as well as its nuich deflected, distal end of the 

 girdle, separate it from E. minor. 



