180 



ASTROPHYTON. 



Ophiomyica pentagona Mull. & Trosch. 



Opkiiira pentarjona Lamk. An. s. Vert., II. p. 54G. 



Ophiomyxa pentiujona Mull. & Trosch. Syst. Asterid., p. 108. 



LIST OF SPECIMENS. 



Catalogue 

 Number. 



Ori^'inal Number 

 Number, of Spec. 



Locality. 



When 

 Collected. 



■Whence obtained. 



Nature of 

 Specimen. 



Museum of Comparative Zoology. 



429 



Alirer. 



Jardin des Plantes. I Alcoholic. 



ASTROPHYTON Linck. 



Type of the Genus, A. arborescens.* 



Disk and arms covered with thick skin, without scales. Radial 

 shields extending nearly or quite to the centre of the disk, and form- 

 ing more or less elevated radial ribs. Two short genital slits in each 

 interbrachial space, lying close to the margin of the disk. Teeth, 

 tooth-papillse, and mouth-papillce all similar and spiniform. Arms 

 forked many times. No arm-spines, except at the tips of the branches, 

 where they have the form of microscopic hooks. Tentacle-scales. Un- 

 der and side arm-plates very small, and buried beneath the skin of the 

 under side of the arm. 



species herein described. 



Disk entirely granulate above ; grains flat ; ribs low, 

 Disk entirely granulate above ; ribs distinct, 



Only ribs closely granulate, 



Ribs with a few short, irregular spines. 

 Disk above closely beset with thorny stumps, 

 Di.sk closely beset above with little thorny spines, 

 High ribs bearing a few clavate stumps. 



arborescens. 



Lamarckii. 



eucnemis. 



Garyi. 



Agassiz'ii. 



Linckii. 



clavatum. 



A. 

 A. 

 A. 

 A. 

 A. 

 A, 

 A. 

 A. costosum. 



* As the specific identification of Linck's plates cannot now be made, I have taken the oldest 

 described species, Stella Arborescens Rond., as the generic type. 



