ACTINIANS OF GULF OF CALIFORNIA— CARLGREN 445 



small daughter polyps, the one connected with the mother by a 

 very thin coenenchyme, the other running out from the base of 

 the mother. The body of the contracted polyps is very depressed 

 so that they show a cakelike appearance. Both sphincters are well 

 developed with rather coarse muscle meshes. Figure 84, i, shows 

 the sphincters of one of the daughter polyps. The ectoderm of the 

 tentacles is provided with very numerous spirocysts in contradis- 

 tinction to that of the tentacles in Z. danae. The mesenteries of the 

 large polyp are apparently about 46 in number. 



Measuremefits. — Largest polyp in contracted state, 0.3 cm. in 

 breadth, 0.1 cm. in height (depressed). 



Holotype. — One colony, U.S.N.M. No. 49443, Cape San Lucas, 

 March 18, 1940. 



SOME ZOOGEOGRAPHICAL CONCLUSIONS 



The upper littoral fauna of the Gulf of California and the waters 

 down to Peru is a warm-water fauna containing, as far as the 

 groups treated here are concerned, such genera as Zoanthus, Paly- 

 thoa, and Phyllactis. These regions have several genera in com- 

 mon, but there are differences too. Three genera, Calamactis, 

 Phialoba, and Isometridium, all new to science, are seemingly 

 endemic in the Gulf of California. To these we may add Bo- 

 truanthus, which, however, occurs in southern California not far 

 from the border to Baja California. Moreover, the genera Neman- 

 thus, Alicia, Gyrostoma, Andvakia, Epiactis, Aiptasiomorpha, and 

 Pachycerianthus are seemingly absent in the waters between 

 Panama and Peru. On the other hand, Isa7'achnanthus, Bartholo- 

 mea {Aiptasia ?), and the dubious genera Nemactis and Anactis 

 occur here but not in the Gulf of California. The genera that these 

 waters have in common are Phymactis, Anthopleura, Bunodosoma, 

 Bunodactis, Phyllactis, Telmatactis, Anthothoe (Verrill's Sagartia 

 species are certainly Anthothoe or Actinothoe but not Sagartia), 

 Zoanthus, Epizoanthiis, and probably Palythoa, though it is diffi- 

 cult to decide if Verrill's Epizoanthus always is a homogenous 

 genus. 



Some authors have raised the question: Does there exist any 

 relation between the fauna of the west side and that of the 

 east side of Central America? How is this applied to the actinians? 

 Unfortunately, the actinian fauna on the east coast of Mexico is 

 unknown, but we know it on the northern coast of the Gulf of 

 Mexico and, have still better knowledge of it from the West Indies, 

 as this fauna has been studied by many authors. Thus, owing to 



