506 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA 



throughout, but in contraction it swells out within the tenaeiilar recess, and at the distal end to 

 such a degree that the latter becomes somewhat capitate. There is no terminal stylet, the distal 

 end being broadly rounded. There is a distinct axial, longitudinal strand, the retractor fiber 

 and a series of equidistant circular fibers, the protractors. The prod was coarsely granular or 

 hispid on its surface in Pavillard's specimen, but not in ours. 



The oeeUus lies to the left of the intercingular region of the sulcus, the anterior 0.8 of which 

 it crowds to the right. Its total length is 0.55 transdiameter and the axis of the lens is about 

 45° from the major axis. The lens is hemispherical, as exposed, iridescent, and is buried rather 

 deeply in the black-pigment mass. This is flattened, with its long axis passing obliquely postero- 

 ventrally. It is somewhat more voluminous or swollen on the ventral and sinistral sides of the 

 lens. No colored core was visible in our specimen, but Pavillard figures a yellowish-brown tint 

 in its center. The ocellus as a whole is more than usually protuberant. 



The nucleus is ellipsoidal (spherical in end view) and lodged far anterior in the epieone in 

 the right dorsal region. Its major and minor axes are respectively 0.65 and 0.5 transdiameters 

 in length. It is hyaline and does not exhibit the moniliform chromatin network usual in the 

 dinoflagellates. The pnsule arises from the anterior flagellar pore and extends posteriorly at 

 the right of the ocellus toward the distal end of the girdle, with another branch running poster- 

 iorly from the pore along the dorsal side of the tentacular recess. In Pavillard 's figure the two, 

 posteriorly located, yellow bodies are probably food pellets. None occurred in our specimen. 

 There were no peripheral vacuoles formed during our observations. The plasm was at all times 

 a translucent, hyaline, dull opaline green, shading into variscite green. Faure-Fremiet 's (1914c) 

 specimens had a faint pinkish tone. 



DiiMEXSioxs. — Length of body, excluding prod, 82m; including extended 

 tentacle. 530/*; length of prod, extended, about 450^; contracted, 90/*: transdi- 

 ameter, 57/*; dorsoventral, 60/*; diameter of lens, 17/*. Pavillard's specimen was 

 smaller, length, 55/*. Faure-Fremiet gives a range of 50/* to 100/* in total length 

 of body. 



OccrP.EEXCE. — A single individual was taken off La Jolla, California, July 

 30. 1917, in a haul with a No. 25 net from a depth of 80 meters to the surface, 

 made 2.5 miles offshore in a surface temperature of about 21° C. Pavillard 

 (1905) observed a single individual taken in plankton from the Etang de Thau, 

 a small bay from the Mediterranean at Cette, France, on October 19. 1904, in 

 surface temperatures of 14-8 C. Faure-Fremiet records (1914) a score of 

 specunens from Croisic, on the west coast of France. 



AcTWiTiES. — The individual observed by us was extraordinarily active. 

 When first brought into view it was circling without noticeable rotation in anti- 

 clockwise spirals about six times its length in diameter. During this time and 

 when at rest its prod underwent ceaseless rhythmical contractions, externally 

 contracting to a length about equal to that of the body and extending as 

 much as five times its length. The rapidity of contraction varied within short 

 intervals. A number of records were made of the mmiber of these contractions 

 for given periods, as follows: 51 contractions in 30 seconds, or 1.7 per second; 

 27 in 10 seconds, or 2.7 per second ; 35 in 20 seconds, or 1.7 per second ; and 14 

 in 10 seconds, or 1.4 per second. These records were made at consecutive inter- 

 vals during the course of a few minutes. They average 2.2 per second. The 

 contractions slowed down and stopped some time before cytolysis occurred. It 

 remained active for nearlv six hours. 



