KOFOID AND SWEZY: UNAKMORED DINOFLAGELLATA 427 



transverse, simple, Avitli elongated lens, and small l)lack melanosome ; al)oiit 30 

 nematof'vsts grouped anteriorly. Length, Si/*. Pacific off La Jolla, Califoi-nia, 

 August. 



Description. — A remarkably specialized species with symmetrically fusiform body widest 

 at the middle and tapering equally towards the two ends, with slightly convex contours between 

 the furrows wliieh noteli its margins four times on either side. Its length is 2.9 its greatest 

 diameter. Tlie ejiicone and hypoeone are subequal in size and volume. Each extends within 

 0.3 transdiameter of the end opposite to itself owing to the extreme torsion of the body. The 

 apex is bluntly rounded, almost hemispherical in form, while the antapex is asymmetrically 

 rounded, being longer on its left, as a result of the asymmetrical dislocation of the posterior 

 end of the sulcus to the left. 



The girdle forms a descending left spiral of 2. 2.5 tiirns, growing steeper as it passes posteriorly 

 from 5° at its proximal end to 50° at its distal junction with the sulcus. The interval of 

 posterior displacement of tlie second turn is five times that of the first and the total distance of 

 vertical displacement is 2.25 transdiameters of 0.78 total length. The furrow is deeply impressed 

 with an overarching anterior lip. The sulcus makes nearly two complete turns. It extends 

 anteriorly above the girdle towards the apex for 0.5 the distance, descends from its junction 

 with tlie proxinial end of the girdle in an ever steepening spiral to its posterior junction with 

 the girdle witliin 0.3 transdiameter of the antapex. It is continued thence, not in a posterior 

 course as usual in the Pouehetiidae, but in a continuation of the spiral which makes another 

 0.5 turn or more around the antapex beyond the posterior flagellar pore. This extension is 

 indistinct. The transverse flagellum traverses, in the moribund state, only the anterior part of 

 the girdle. The posterior flagellum arises from the pore at the posterior junction of girdle and 

 sulcus and extends directly posteriorly, not in the spiral continuation of the sulcus around to 

 the opposite side of the body. 



The ocellus is 0.25 of the total length from the antapex, at the left of the pasterior part of 

 the interciugular sulcus, lies transversely and is directed to tlie left with its oiiter end somewhat 

 protuberant. Its length is 0.6 transdiameter. It consists of an elongated, transparent, glaucous- 

 blue lens with eight cupped lamellae and a very small, curved, bandlike melanosome across its 

 adsulcal end. Its constituent parts are more correctly represented in figure NN, 3, than in the 

 colored figure (pi. 11, fig. 124). No distinct colored core was detected. 



The nematoeysts are about thirty in number, arranged in two irregular circles around the 

 anterior third of the body peripheral to the nucleus. They are all pointed anteriorly. They 

 are yellowish green in color and in form are peg-shaped sti-uctures, 0.16-0.25 transdiameter in 

 length, and their length is 2.5 to 4 times their greatest diameter which is anterior. There was 

 no nuchal constriction delimiting a capitate end. The interior of the capsule is fluid-filled and 

 contains the introvert consisting of the shaft and its spiral continuation coiled about it. On 

 cytolysis of the body the nematocyst is discharged and forms a fiat close spiral a little longer 

 than the capsule. 



The nucleus is elongated ellipsoidal, its major and minor axes being 0.9 and 0.5 transdiameter 

 respectively in length. Its major axis coincides with that of the body. It lies just anterior to 

 the middle of the body. No pusules were noted. Behind it is a spherical food vacuole containing 

 an oehraceous food ball with two dark ochraeeous chromatophores. A black spherical pigment 

 grain lies near the apex and scattered about it are some smaller greenish oil globules, while larger 

 liighly refractive globules presumably of an oil}' nature lie near the antapex. The general color 

 of the plasma is an exceedingly transparent, pale glaucous blue. 



Dimensions. — Length, 83m; greatest transdiameter, 29/s length of nucleus, 

 28f* ; of ocellus, 18^ ; of nematoeysts, 5-8/*. 



