ACTINIANS OF GULF OF CALIFORNIA— CARLGREN 439 



mesenterial canals. Figure 82, e and /, shows the basal parts of two 

 macromesenteries with their canal system and holotrichs (the pig- 

 mented cells not figured, /-filament) . Nematocysts of the tentacles 

 45-57.8 by 22.6-28.2 ^u, (holotrichs) ; those of the actinopharynx 

 24-29.6 by about 4.2 /x (microbasic 6-mastigophors) ; those of the 

 filaments partly 56-65 by 19.7-22.6 ii (holotrichs), partly (18.3) 

 21.1-24 by 4.2-5.6 /a (microbasic 23-mastigophors) , partly 37.4-47.9 

 by 5.6-6 /A (microbasic 5-mastigophors) ; those of the mesenterial 

 canals 52.2-63.5 by 22.6-25.4 fx (holotrichs). 



Color in alcohol. — Brownish gray. 



Measurements. — Larger polyps, breadth 0.9 cm., breadth of 

 colony 5 by 6 cm. 



Holotype. — One colony, U.S.N.M. No. 49455, Puerto Escondido, 

 March 26, 1940. 



Remarks. — A great area of rock and sponge was covered with 

 these colonies. 



PALYTHOA PRAELONGA, new species 



Figure 82, g, h; Plate 14, Figure 10 



Solitary, extraordinarily elongate polyps, narrow in their lower 

 part increasing in breadth toward the scapulus (pi. 14, fig. 10). 

 About half to two-thirds of the mesogloea of the column incrusted 

 with grains of lime. Mesogloea of the column with cells and cell- 

 islets showing tendency to a ringlike arrangement toward the 

 endoderm. Ridges of the scapulus about 32 or more, incrusted. 

 Sphincter forming a row of very large, broad muscle meshes 

 drawn out transversely (fig. 82, g, part of the sphincter) . Tentacles 

 with spirocysts. Siphonoglyph well developed, hyposulcus short. 

 Mesenteries of the largest specimen about 72 ; without pigmented 

 cells in their canal system, which probably does not contain any 

 holotrichs in its lower part but has some in its upper (see fig. 82, h, 

 which shows a section of the column in its upper part) . Owing to 

 the smallness of the mesenteries at the base, it is very difficult to 

 determine if holotrichs are present; if so they may be very rare. 

 Nematocysts of the column partly 19.7-33.8 by 5-5.6 fi (micro- 

 basic 29-mastigophors, very rare) , partly 18.3-21 by 3-3.5 fi (micro- 

 basic &-mastigophors) ; those of the tentacles partly 22.6-32.4 by 

 4.5-5 IX (few, microbasic ??-mastigophors), partly 21.1-25.4 by 

 about 3 fj. (microbasic &-mastigophors), partly 48-49.3 by 21 fi 

 (holotrichs — probably in endoderm) ; those of the actinopharynx 

 32.4-39.5 by 4.2-5 /a (microbasic ft-mastigophors) ; those of the 

 filaments partly 25.4-38 by 4.2-7 /x (microbasic ??-mastigophors), 

 partly 38.8-53.6 by 4.2-5.6 /x (microbasic 6-mastigophors), partly 

 48-56.4 by 23.3-24 /* (holotrichs, rather scarce) . 



