^OL. 3] Kofoid. — Triposolenia. 103 



proportion is preserved alike in slender and in more robust indi- 

 viduals. There is thus apparently a correlation in the develop- 

 ment of the three regions. 



The length of the antapieals is 2.5-3.25 times the distance 

 from the center of the midbody to their bases. Their curvature is 

 greatest in the middle third of their course and is sometimes 

 slightly localized in a knee, though the curvature as a whole is 

 more uniform than in the other species. The distance between 

 the tips is 2-2.25 times that between the bases and that between 

 the outer margins of the knees 1.15-1.2 times that between the 

 inner spinules of the tips. The ends are squarely truncate and 

 each bears on the dorsal and ventral angles at the suture line a 

 pair of slender divergent spinules not over half the diameter of 

 the antapieals in length. Sometimes the outer spinule alone is 

 present and is larger than usual. The dorso-ventral diameter of 

 the antapieals at the tips is 0.5-0.7 that of their bases and the 

 mean diameter varies from 0.1 of the total length in robust indi- 

 viduals to 0.06 in more slender ones. Their length varies from 

 1.6 to 1.8 times the diameter between their bases and 1.5 to 1.7 

 times the altiude of the midbody measured from the base of the 

 anterior process to the middle of the posterior margin. The distal 

 fourth of the antapieals is deflected slightly to the left. 



The anterior prolongation consists of the head, neck, and a 

 short extension of the midbody to the flagellar pore, the latter 

 forming 0.3-0.4 of the total length of the process. The region of 

 the cytopharynx is strongly protuberant ventrally, but the pro- 

 jection recedes more or less before its junction with the midbody. 

 The diameter at the cytopharynx is nearly twice that of the neck. 



The head is elongated, depressed, and slightly oblique, and its 

 long axis is 0.6 of the length of the neck. The anterior face of 

 the epitheca is quite concave, and the transverse furrow is some- 

 what impressed. The transverse lists are low, spreading, and the 

 anterior one is faintly ribbed with 10-12 ribs. The longitudinal 

 lists embrace the flagellar pore. The left one is continued beyond 

 the pore nearly to the midbody, and has a suture spine below the 

 pore and several accessory spines distally. 



The thecal wall is pitted (pores?) profusely, but more spar- 

 ingly towards the tips of the antapieals and the base of the ante- 



