518 EDITH M. PRATT. 



Throughout the genus the tentacles are short, blunt, and stumpy, compared with other 

 genera. They vary slightly in size in different species (Table, p. 531) and in some cases are 

 extremely small. They are only slightly pinnate, and in Sc. gardirieri the pinnules are ex- 

 tremely rudimentary. Owing to the contracted condition of many of the specimens it was 

 found impossible to determine the actual length and pinnate character of the tentacles of 

 some of the species. In 8c. capitate and Sc. palmatum, which have comparatively large 

 tentacles, some of the autozooids are expanded. In both of these species a double row 

 of very small pinnules was seen on each side of the tentacles (figs. 17 and 27) ; in this 

 respect this species approaches the genus Xenia. 



The stomodaeuni is comparatively long and has a well-marked siplionoglyph in every 

 species of the genus. The mesenteries differ in size, in Sc. palmatmn, Sc. hirtmn, and Sc. 

 capitale being well marked, in Sc. densum, Sc. polydactylum, Sc. durum and Sc. querciforme 

 long and slender, but in Sc. gardineri only the dorsal ones well marked. The dorsal 

 mesenterial filaments are long, broad, grooved and ciliated in every species, but the ventral 

 and lateral vary in size in different species. These filaments are often very short and feebly 

 developed and are never long or well marked (Table, p. 531); in Sc. gardineri they are 

 apparently absent. The small size or entire absence of ventral or lateral mesenterial filaments 

 is probably correlated with the presence of numerous zoochlorellae, for they are most numerous 

 in Sc. gardineri, which has no ventral or lateral filaments. 



Reproductive cells are not present in all the specimens, and where they do occur they 

 consist entirely of female cells. I have not been successful in obtaining a single specimen 

 with male cells. The ova appear to be of the typical Alcyonarian type, but the occurrence 

 of ova on the dorsal mesenteries of Sc. gardineri is interesting (pp. 527 — 8). 



Siphonozooids are present and are numerous in many but not in all species of the 

 genus. They are very small compared with those of Sarcopliytum and Lohophytum and show 

 unmistakable signs of degeneration. They are largest in Sc. capitale where they have an 

 average length of '3 mm. (figs. 17 and 19, si.), but they are not difficult to recognise in 

 stained preparations or sections of Sc. densum, Sc. hirtum, and Sc. palmatum, in which they 

 vary from "1 mm. — '17 mm. in length. In all these species they have small stomodaea which 

 usually open to the exterior (figs. 19, 21, 22, 25, m. ap.), but this is often difficult to see 

 except in stained sections. Traces of mesenteries occur in many of the siphonozooids. As 

 a rule a siphonozooid terminates posteriori}' in a large transverse vessel of the superficial 

 canal system. 



In >S'c. durum and Sc. polydactylwm the degeneration of the siphonozooids has proceeded 

 much further than in Sc. capitale, Sc. densum, Sc. hirtum, and Sc. palmatmn. In these two 

 species the siphonozooids are represented by very short vertical caeca from the superficial, 

 transverse canals. Traces of a stomodaeuni may often be seen in an aggregation of ectoderm 

 cells between the terminal portion of the caeca and the surface of the colony, but I have 

 not observed any apertures to the exterior, nor any traces of mesenteries. Sc. gardineri and 

 Sc. querciforme are similar anatomically in many respects to other species of this genus, 

 but are more degenerate in character, and have completely lost their siphonozooids. In Sc. 

 gardineri the autozooids also exhibit slight signs of degeneration. 



Canal-systems and formation of zooids by budding. The transverse superficial 

 and the internal canal systems can be easily distinguished in decalcified moderately thin 

 free-hand sections, mounted simply in glycerine jelly or stained with borax carmine or 



