'iS'i DENDROCHIROTAE. 



23. Ptolug fahricii LÜTKEN (DÜBEN et KoREN sp.) 



Cuvieria fabricii Düben och Koren. X. Vetensk. Akad. Handling, 

 (for 1844) 1846. p. 316. — Psolus fabricii Lütken, Oversigt 

 over Grönlands Echinodermata. 1857. p.p. 13 — 15. — Semper, 

 Holothurien. 1868. p. 272. — v. Marenzeller, Coelenterat., 

 Echinod. u. Würmer der öst.-ung. Nordpol-Expedit. Wien. 

 1877. p. 32. 



Three ^ecimens from Greenland , one from Grand Manan , 

 and one from the Bay of Massachusetts , the latter from a 

 depth of 20—30 fathoms. 



24. Thyone briaveus Selenka (Lesueur sp.) 



Holothuria briareus Lesueur, Journ. Acad. Nat. Sc. Philadelphia. 

 Vol. IV. 1824. p.p. 161—162. — Thyone briareus Selenka, 

 Zeitschr. f. wissensch. Zool. XVII, 1867, p. 353. — Semper, 

 Holothurien. 1868. p.p. 272—273. 



Two specimens from Charleston. 



25. Thyonidiutn tnagnutn n. sp. 



The only available fragment , obtained at Amboina , 

 coilsists of no more than the anterior body-region , mea- 

 sures 7.5 cm. in length and encloses no internal organs 

 except the pharynx. The colour of the whole fragment is 

 bright yellowish brown , the tube-feet and the tentacles 

 being of a darker brown. Round the mouth are placed 

 twenty larger and smaller tentacles , arranged in the way 

 which is characteristic for the genus; the five pairs of 

 large tentacles are 7 mm. thick at their root and are 

 45 mm. long ; the five pairs of small ones , alternating 

 with the others are 2 mm. thick at their root and are 

 7 mm. long. The insertion of the small tentacles is some- 

 what farther inwards than is that of the large ones. The 

 calcareous ring has a length of 7 cm. ; it is elongated 

 posteriorly and spirally coiled , as is also the case in other 

 species of this and of the allied genera (Cucumaria , Thyone). 

 At the posterior end of the calcareous ring is suspended a 

 water-tube (stone-canal) which is 2 cm. long and ends in a 

 small truncated protuberance, and 4 tubular Polian vesi- 



r<J'otes from the Leydèn IVttiseuna, Vol. IV. 



