KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 443 



Pouchetia fusus Scliiitt 



Text figure PP, 1 



Pouchetia fusus Schiitt (3S95), p. 96, pi. 26, fig. 94; (]896), p. 6, fig. 8. 



P. fusus, Delage et Heronard (1896), p. 384, fig. 668. 



P. fusus, Lemmermann (1899), p. 360. 



P. fusus. Cavers (1913), pp. 182, 183, fig. 9„. 



P. fusus, Liihe (1913), p. 230, fig. 230, ocellus lacking. 



P. fusus, Lebour (1917&), p. 198. 



Diagnosis. — A medium sized species with fusiform Ijody, its length 2.33 

 transdiameters ; girdle a descendiug left spiral of 2 turns, displaced 1.33 trans- 

 diameters: sidcus with 1 turn, without anterior and posterior loops; ocellus 

 premediau with bipolar lens and circular equatorial pigment mass. Length, 

 94^*. Bay of Naples or Atlantic ( ?) ; Plymouth Sound, England, September. 



Description. — The body is stout fusiform, widest at the middle, more tapering posteriorly, 

 its length 2.33 transdiameters at the widest part. The epicone has a length at its left and right 

 sides of about 0.20 and 0.75 respectively of the total length of the body. It is thus a trifle 

 shorter than the hypoeone, but being stouter anteriorly has about the same volume as the longer 

 hypocone. The anterior part is convex conical (55°) with rounded apex. The hypoeone is more 

 tapering (50°), less rounded at the antapex and somewhat less symmetrical. The dorsoventral 

 and transverse diameters are equal. 



The girdle begins at the anterior flagellar pore, located at its junction with the sulcus, about 

 0.2 total length of the body from the apex, forms a descending left spiral of almost two full 

 regular turns, with a total displacement of 1.33 transdiameters or 0.56 total length. The furrow 

 is deeply impressed and has a width of 0.14 transdiameter. The sulcus begins a short distance 

 below tlie apex of the e])icone, runs posteriorly to the junction with the girdle, and turns in a 

 descending left spiral for nearly a full turn to its posterior junction with the girdle, beyond 

 which it runs posteriorly nearly to the antapex in the median plane. There is thus neither an 

 anterior nor a posterior loop, and there is no sulcal notch at the antapex. Both flagellar pores 

 are near the midventral line. The transverse flagellum makes more than one turn and the 

 longitudinal exceeds 0.5 of the length of the body. 



The ocellus is peculiar in two respects: its location is deep in the cytoplasm almost in tlie 

 axis of the body anterior to the middle and to the greatest diameter, and it is bipolar. Its length 

 is about 0.65 transdiameter and its axis is almost parallel to, or coincident with, the axis of the 

 body (without torsion). The narrow intervals between the turns of the girdle and sulcus do 

 not permit so large a lens to occupy the usual peripheral position at the immediate left of the 

 sulcus. It thus appears to be forced into the interior by tlie torsion of the narrow body. It 

 consi.sts of a bipolar lens with an encircling equatorial pigment mass. The ex]iosed ends are 

 spheroidal, about 0.3 transdiameter in diameter, of e(iual size, with about 0.25 diameter covered 

 by the pigment mass. This is a ringlike structure, the diameter of which is 1.2 and tlie length 

 about 0.6 of that of a lens. It is black with a reddish brown center. Lebour (19176) says it is 

 dark red and was seen breaking up into small red spots in one case. Except for a small globule 

 of black pigment on the posterior lij) of the girdle on the dorsal side no other structures are 

 noted by Schiitt (1895). 



DiMF.xsioxs. — Length, 94^; transdiameter, 41^^; length of ocellus. 21/^. 



OccuBRExcE. — Figured by Scliiitt (1895) from the collections of the IMank- 

 ton Expedition, presumably from the Bay of Naples or the Atlantic. The only 

 other record is that of Miss Lebour (1917?;), who reports it as rare in September 

 in the plankton from Plymouth Sound, England. 



