KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 449 



The sulcus takes origin in a rounded depression only slightly above the anterior flagellar 

 pore. It sweeps around the bodj' as a narrow shallow trotigh about 0.33 the width of the girdle 

 for 0.75 of its circumference, ending on the right margin of the dorsal side of the antapex. The 

 sulcus widens to three times its width above, after its posterior junction with the girdle. 



The ocellus is situated on the ventral face at the left of the sulcus, slightly anterior to the 

 equator. Its length is about 0.25 transdiaraeter and its axis horizontal. It is directed to the 

 left. It consists of a hemispherical melanosome with a rufous central core in which the base of 

 tlie smaller lens is embedded. Near the lens is a horizontal row of five unequal, highly refractive 

 spherules appressed in one mass, the one nearest the lens being a nearly spherical hyaline mass. 

 They ai'e composed of greenish opaque material resembling the lens in color but less hyaline. 

 They appear to be ])roducts of metabolism rather than parts of a lens of the diffuse type. Several 

 masses of rufous-black pigment are scattered along the anterior border of the girdle below the 

 ocellus. 



The nucleus is large, spheroidal, ovoidal or ellipsoidal, and centrally located. Distinct 

 chromatin sti-ands follow its major axis. Its major and minor axes are 0.7-0.9 and 0.6-0.4 

 transdianieter in length respectively. 



A small ovoidal pusule opens anteriorly into the anterior flagellar pore. The cytoplasm is 

 finely granular with few to many food vacuoles. In the individual figured the irregular wrinkled 

 skirt of protoplasm protruding from the antapex is the discharge vent opened by the ejection 

 of a large food nuuss. The same appearance has been noted in other forms with the actual 

 discharge of a food mass. Later it was completely retracted in the individual figured. 



The surface of the body presents a number of distinct longitudinal striations on the hypoeone, 

 sixteen on one face. There are faint indications of striae on the central section of the epicone, 

 but none elsewhere. There are no peripheral vacuoles other than slight accumulations along 

 the striae. 



The color is a pale lavender diffused through the cytoplasm, being more dense at the periphery 

 than throughout the main body and a trifle darker anteriorly, suggesting an axial gradient in 

 metabolism. 



Dimensions.- — Length, 145/*; transdiameter, 92/*; axes of nucleus, 60/* and 

 63/* ; length of ocellus, 20^. 



OcciTEEEXCE. — One individual was taken in a hatd made 4 miles off La Jolla, 

 California, on July 11, 1917, with a No. 25 silk net from 80 meters to the surface 

 and in a surface tempei'ature of 19°1 C. 



AcxrviTiES. — The turns of the spiral of the contracted transverse flagellum 

 were very close set and the waves of contraction running through it distally 

 were extraordinarily rapid. The animal moved intermittently in clockwise 

 circles of a diameter several times its length, withotit rotation on its axis. The 

 progress was noticeably intermittent and jerking and is due either to the tem- 

 porary attachment of the trailing flagellum to the substrate or to its intermittent 

 action, apparently to the latter primarily. 



Comparisons. — This is a very highly specialized representative of the sub- 

 genus Pouchetia with integrated ocellus. Both lens and melanosome are com- 

 pact and their union is intimate. In volume also it is a large species, in fact 

 the largest in the genus. It shares the sti'uctitral features of median ocellus 

 of integrated type in a horizontal position and large size of body with P. Jkiio 

 (fig. 00, 3) and P. violescens (fig. 00, 1). It differs from them in one im- 

 portant feature, namely, the very great displacement between the proximal and 



