Revision of the Holothurioidea. 349 
longitudinal muscles, somewhat back of the middle of the body in a 
contracted specimen. Each retractor is inserted upon the anterior 
projection of the related radiale. In some cases the simple retractor 
muscle divides into a pair of bands. 
The eircular muscles and the cloaca extensors are well developed. 
Enteric canal. — ÖsTERGREn, 1907, shows how prone we 
are to take for granted as true the long accepted descriptions of 
anatomical structures. This author finds (1898), contrary to the 
established rule for holothurians in general, that in the Cucumariidae, 
except the Psolinae, the mesentery of the third enteric loop is at- 
tached to the left of the mid-ventral radial muscle and the third 
loop really belongs to the mid-ventral radius. I too find this 
attachment to the left of the radial muscle of the mid-ventral radius 
in Cucumaria frondosa and other species of the genus Cucumaria. 
In some specimens of Cucumaria frondosa the mesentery is found on 
the muscle band itself for the posterior third of its course. 
In agreement with ÖsTERGREN, 1898, I do not find Cuvierian 
organs as described by JoH. MÜLLER. 
Habitat. — Two-thirds eircumpolar; south to Britain in the 
eastern Atlantic; to some 60 miles south and a little east of Nan- 
tucket Island, Mass. (lat. 40° 19' 30“ N., long. 69° 29° 10“ W.); also 
once reported by PourrTAuks, 1869, of Florida in 115 fathoms, in 
the western Atlantic. 
Lupwıs, 1900, gives an admirable statement of the details of 
the geographical distribution up to that time. The occurence of 
Cucumaria frondosa in the Pacific Ocean was reported by AyYres, 
1855, but was questioned by VeErrRILL, 1867, Lupwıc, 1900, and 
CLARK, 1904. In my paper of 1907 this species was given from the 
Pacific but since then from my work on the large collections of the 
United States National Museum, I have concluded that there are 
at least four species in the Pacific similar to but distinet from 
Cucumaria frondosa. One of these is Cucumaria japonica SEMPER, 
1868, while the specimens identified as of this type by LAmPperr, 
1885, Crark, 1902, and Epwarps, 1907, belong to a second form, 
Cucumaria miniata BBANDT, 1835. 'The other 2 species are (ucumaria 
californica SEMPER, 1868, and Cucumaria fallax Lupwis, 1874. 
Würzburg, Jan. 8, 1910. 
