4 
Explanation. — Stelleroidea. 
Pars 3 
Explanation of terms and symbols nsed in the 
catalogue. 
(A) = Asteroidea 
(AL) = Auluroidea 
(0) = Ophiuroidea. 
Genotype (genos- race, and typos -type). Genotype applies to the selected 
type species on which a genus is based. The selection may 
come about by any one of four methods; 
(1) Genoholotype or „type by designation“. The one species fixed 
by an author as the type of a genus. In cases where the genus 
at the time of original definition contained but a single species, 
this naturally becomes the genotype even if the author fails to 
state its selection („type by monotypy“). 
(2) On the other hand, when the name of a genus is the same as 
that of one of its original species, or the same as a synonym of 
one of its species, that species must be accepted as the geno- 
holotype („type by tautonymy“ of Allen). 
(3) Genosyntypes. Two or more species mentioned by the author 
at the time of original definition, without selection of any one as 
the type. These genotypes may be monotypical or heterotypical. 
When one of these forms is selected by a subsequent worker it 
becomes a 
(4) Genolectotype or „typs by subsequent designation“ or „type by 
revision“. 
The literature on this subject is as follows: „0n type specimens in 
natural history“, by Charles Schuchert (Bull. 53, U. S. Nat. Mus., Pt. I, 
1905, pp. 7 — 18); and „Tlie determination of genotypes in Zoology“, by 
J. A. Allen (Proc. Seventh. Inter. Zool. Cong., Boston, 1912, pp. 807 — 813). 
The catalogue recognizes the folio wing Stelleroidea: 
Geograpliic Distribution 
Genera 
Species 
North 
American 
Species 
European 
Species 
Southern 
Hemisphere 
Species 
Asteroidea .... 
45 
108 
51 
51 
6 
Auluroidea . . . 
30 
55 
17 
33 
5 
Ophiuroidea . . . 
1 
5 
5 
0 
0 
Totals 
76 
168 
79 
84 
1 11 
Greologic Distribution 
Ordo- 
vicic 
(Untersilur) 
Siluric 
(Obersilur) 
Devonic 
Lower 
Carboni- 
ferous 
Upper 
Carboni - 
ferous 
Permic 
Asteroidea. . . . 
45 
16 
35 
6 
6 
0 
Auluroidea . . . 
12 
16 
24 
3 
0 
0 
Ophiuroidea . . 
0 
0 
0 
5 
0 
0 
Totals 
57 
32 
59 
14 
6 
0 
