422 PROCEEDINGS OF THE NATIONAL MUSEUM vol. m 



weak. Nematocysts of the columns 14-18.3 by 2.5-2.8 /a (basit- 

 richs) ; those of the tentacles 15.5-22.6 by 2.2-2.5 /x (basitrichs) ; 

 those of the actinopharynx partly 21-28 by about 3 /a (basitrichs) , 

 partly 19-22.6 by 4.5-5 fx (microbasic p-mastigophors) ; those of 

 the filaments partly 19-33.8 by 5.6-6.3 [x, partly 11.3-16.2 by 2.8 

 (few, both basitrichs), partly 21-24 by 4.2-5 /x (microbasic p-msLS- 

 tigophors) . 



Measurements. — The largest specimen, height 1 cm., breadth 1.8 

 cm. 



Cotypes. — Two specimens, U.S.N.M. No. 49451, San Carlos Bay, 

 Sonora, Mexico, March 30, 1940. 



Remarks. — The larger, fertile specimen provided with two 

 siphonoglyphs, not symmetrically set, has 118 tentacles; the 

 smaller, sterile specimen, about 96. I have drawn the sphincter of 

 the sterile individual (fig. 79, a.). 



EPIACTIS IRREGULARIS, new species 



Figure 79, b, c 



Tentacles about 70. Sphincter restricted (diffuse circum- 

 scribed) . Pairs of mesenteries 6 -}- 6 + 12 -|- 12, the mesenteries 

 of the last cycle absent in the exocoels next to the mesenteries of 

 the first cycle. Same number of mesenteries proximally and dis- 

 tally. Nematocysts of the columns partly 8.5-11 by 2.2 /*, com- 

 mon, partly 15.5-18.3 by 2.5 /.l, common, a few 21-25 by 2.8 fx (all 

 basitrichs) ; those of the tentacles partly 8.5-11.3 by about 2.2 /x, 

 partly 18.2-26.8 by 2.8 /x (all basitrichs) ; those of the actino- 

 pharynx partly 21-26.8 by 3 ^u (basitrichs), partly 19.7-21.8 by 

 4.2-5.5 ju. (microbasic 29-mastigophors) ; those of the filaments partly 

 11.3-18.3 by 2.2-2.8 ^, partly 38-43.7 by 3.5-4.2 /x (both basit- 

 richs), partly 18.3-22.6 by 4.2-5.5 /x (microbasic p-mastigophors) . 



Measurements. — Length and breadth about 1.1 cm. 



Holotype.— V.S.N. M. No. 49446, east of La Paz, March 21, 1940. 



Remarks. — The sphincter (fig. 79, b) is almost restricted with 

 the strongest folds distally. It has quite a different appearance 

 from that of Epiactis prolifera, the sphincter of which seems to be 

 fairly constant. I have examined the sphincter of two specimens 

 of the latter species, one from Santa Cruz, provided with embryos 

 on the column, and another from Puget Sound, and both agree 

 in the main with that figured by Torrey (1902). The tentacles 

 are of normal size and between 70 and 80 in number. The arrange- 

 ment of the mesenteries in half of a specimen is 1 (directive), 

 3, 4, 2, 4, 3, 1, 3, 4, 2, 4, 3, 1, 3, 4, 2, 4, 3, 1 (directive). Twelve 

 pairs of mesenteries are perfect. There are the same number of 

 mesenteries proximally and distally. The retractors are restricted, 



