REPORT ON THE TETRACTINELLIDA. CXXXvii 
Notwithstanding its want of completeness this arrangement has a good deal to 
recommend it ; a particularly good distinction is the primary one into Psilodermata and 
Pycnodermata. The Stellifera would include our Myriastra and Anthastra ; the Bacillifera 
the single genus Ecionema, Bwk. 
The Discifera are equivalent to the genus Erylus of the Geodiidse ; the Globostellata 
to the new genus Aurora. 
In redistributing the contents of the family, regard has been paid to the general 
assemblage of characters, and the genera now proposed will, I think, prove to be natural ; 
there are some which are more doubtful than others, on account of their being founded 
either on single species or on single characters ; such are Astrella, distinguished from 
Stelletta by possessing but one form of aster ; Anthastra, distinguished from Myriastra 
by the presence of a second aster (the anthaster). The grouping of the genera into 
subfamilies depends chiefly on the characters of the asters. 
Subfamily 1. Homasterina ; Stellettidse which never possess more than one form of 
aster, 
a. Ectosome not a cortex — Myriastra. 
h. Ectosome a fibrous cortex — Pilochrota, Astrella. 
In the remaining genera more than one form of aster is present, they may therefore be 
termed “ heterastrose,” 
Subfamily 2. Euasterina ; heterastrose Stellettidse in which the additional microsclere 
is a euaster. 
a. Ectosome not a cortex — Anthastra. 
h. Ectosome a fibrous cortex — Stelletta, Dragmastra. 
c. Ectosome crowded with large spherasters, but not fibrous — Aurora. 
Subfamily 3. Ehabdasterina ; heterastrose SteUettidse in which the additional micro- 
sclere is a microrabd. 
a. Ectosome not a cortex — Ecionema. 
b. Ectosome a fibrous cortex — Psammastra. 
c. Ectosome crowded with microrabds — Papyrula, Algol. 
Subfamily 4. Sanidasterina ; beterasterose Stellettidse in which the additional micro- 
sclere is a sanidaster or amphiaster, 
a. Skeleton radiately arranged, ectosome a fibrous or fibro-spicular cortex — 
Ancorina, Tribrachium, Disyringa, Tethyopsis. 
b. Skeleton with no regular arrangement, ectosome a spicular not a fibrous 
cortex — Stryphnus. 
(ZOOL. CHALL. exp. — PART LXIII. — 1888 .) 
Rrr s 
