KOFOID AND SWEZY: UNAKMORED DINOPLAGELLATA 207 



is that of a sigmoid curve, forming a shallow trough which soon fades out. The anterior flagellar 

 pore is found at the proximal junction of the girdle and sulcus, the posterior pore a very short 

 distance beyond the distal junction. 



The nucleus is elongated, somewhat reniform, its long axis coinciding with the shoi-t axis of 

 the body. It is filled with rather large, moniliforni chromatin threads following its long axis. 

 Its major and minor axes are 0.6 and 0.36 transdiameter in length respectively. 



A large, ellipsoidal pusule is situated in the posterior part of the hypoeone and opens into 

 the anterior flagellar pore by a long narrow tube. The cytoplasm is finely granular. Scattered 

 through it are small vacuoles filled with fluid of the color of the pusule. Near the surface and 

 at right angles to it are numerous small, greeni.sh rodlets. A large yellowish food mass was 

 found in the antapical region. The general color of the body is bluish grey, shading to orange 

 in the peripheral zone. Nutrition is liolozoic, as indicated by the presence of ingested food 

 masses. 



Dimensions. — Length, 59m; transdiameter, 41^^; axes of nncleus. 25/^ and 15m. 



Occurrence. — One individual was taken on July 2, 1917, with a No. 12 

 silk net in a haul taken 6 miles off La Jolla, California, from 20 meters to the 

 surface and in a surface temperature of 21 ?4 C. 



Comparisons. — In its ])eripheral zone of short radial rodlets this species 

 resembles some species of Gi/rodtJiinni, such as G. fissnin and G. heferostriatum, 

 though the rodlets are fewer in numlier than in the case of the latter species. 

 They are probably concerned with the metabolism of the cell. In the anterior 

 location of the girdle and the consequent reduction in size of the epicone it 

 resembles G. fulgcus, G. coiiicion, and G. psci((]niioctih(ca (fig. X, 30, 27, 35). 

 It belongs to the suljgenus Gumuodinimn, though its proportions are near to 

 those of the striate species included in Lineadinium (fig. Y), especially to G. 

 gracile Bergh (fig. Z, 3) and G. heterostriatmn (fig. Y, 7). However, it is 

 wholly devoid of striae. It resembles G. ravencscens in size, displaced girdle, 

 and short sulcus, but has a more tapering hypoeone, and lacks chromato])hores. 



Gymnodinium filum Lcljour 



Text figure X, 20 

 Gymnodinium filum Lebour (19176), p. 193, fig. 9. 



Diagnosis. — A small, slender species with biconical body, its length 4.06 

 transdiameters ; girdle anterior, without displacement ; sulcus short on epicone, 

 long on hypoeone, reaching to within a short distance of the antapex ; colorless. 

 Length, 65m. Plymouth Sound, England, July. 



Description. — The body is long and slender, tapering to a threadlike point posteriorly, 

 widest anteriorly, its length 4.06 transdiameters at the widest part. The dorsoventral diameter 

 is slightly less than the transdiameter. The hypoeone exceeds the epicone in length by about 

 0.74. The epicone is conical, al)out 60°, Avith narrow, blunt apex. Its length is about 0.2 of 

 the total length of the body. The transdiameter of the base is very slightly greater than its 

 height. The hyi)ocoue is long, slender conical, its angle about 20° and its length slightly moi'e 

 than three times its greatest transdiameter. The antapex is drawn out into a long, slender point. 



