124 



ACTINIARIA 



however, think that the species is a Halcampa as it agrees well with other characters of this genus. The pen- 

 nons of the perfect mesenteries are very much branched, as the textfigure 146 shows. The parietal muscles 

 (textfig. 147) are more ramificated than in H. arctica, so are also the muscles of the imperfect mesenteries 

 (textfig. 148). The parietal muscles are not elongated as in H. arctica, but more transversely spread, possibly 

 on account of a different contraction of the muscles. 



Whether this form is in reality a species different from H. arctica I cannot at present decide 



Genus Cactosoma Dan. 



Diagnosis: Halcampidae with the column divisible into three regions, physa, scapus and capi- 

 tulum. Physa small, often flattened, not ampullaceous, probably without pores. Scapus with a cuticle and 

 "Halcampa-papillae". Capitulum with comparatively sparse spirocysts. Sphincter simple, weak, expanding 

 a little into the base of the tentacles. Tentacles short, more than 12. Actinopharynx short, without distinctly 

 differentiated siphonoglyphes. Mesenteries arranged in two or several cycles. Only the mesenteries of the 

 first cycle perfect, fertile and furnished with longitudinal muscle-pennons. Mesenteries of the second (and 

 other) cycles sterile, without pennons and filaments, extended over the whole length of the column. 



This genus is synonymous with Phelliomorpha, proposed by myself 1902 (compare below under Cac- 

 tosoma abyssorum). As the above diagnosis clearly shows, this genus is nearly allied with Halcampa, and con- 

 sequently it is not a transition form to the Zoanthidae, as declared by Danielssen (1900, p. 85). In addi- 

 tion to the type, Cactosoma abyssorum Dan. (= Phelliacrassa Dan.), I refer to this genus a hitherto undescribed 

 species from the coast of California (Cactosoma arenaria) and Halianthus chilensis Me. Murr. Me. Murrich 

 (1904, p. 224) namely says about this species "The sphincter seems to have been imbedded in the mesogloea, 

 for just below the line of insertion of the outer tentacles there was in the column-wall a narrow band of what 

 seemed to be muscle tissue, enclosed within the mesogloea and separated by narrow bands of it from both 

 the ectoderm and the endoderm". 



Cactosoma abyssorum Dan. 



Cactosoma abyssorum, n. sp. Danielssen 1890, p. 82, PI. 6, fig. 5, PI. 23, figs. 5 8. 



Phettia crassa n. sp. Danielssen 1890, p. 60, PI. 4, fig. 9, PI. 13, figs. 5, 6, PI. 14, figs, i 5. 



Isophellia crassa (Dan.) Carlgren 1900, p. 52. 



Phelliomorpha crassa (Dan.) Carlgren 1902, p. 44, textfigs. 7 n. 



Diagnosis: Body elongated. Typical nematocysts in the ectoderm of the scapus 10 16 x 2 (2,5) p, 

 in the capitulum 20 26 X 2,5 p, in the tentacles 1422 X 2 2,5 (3,5) n and in the actinopharynx about 

 14 29 p. in length. In the ectoderm of the latter, nematocysts with discernible basal part to the spiral thread 

 22 33 X 4,5 5 [JL in size. Spirocysts in the ectoderm of the capitulum sparse, in the tentacles very com- 

 mon 24 x almost 2 36 X 2,5 (i spirocyst 43 X 4 ft). Tentacles 24 (6 + 6 -f 12), the inner about one third 

 longer than the outer. Longitudinal muscles of the tentacles and radial muscles of the oral disc ectodermal. 

 strong, with palisade-shaped folds. Actinopharynx longitudinally plicated. Two cycles of mesenteries. Lon- 

 gitudinal pennons on the perfect mesenteries strong, in the reproductive region with about 20 30 high, 

 rather richly ramificated folds. The outer parts of the mesenteries issue not far from the outer side of the 



