560 THE VOYAGE OF H.M.S. CHALLENGER. 
laster paleocrystallus* than to any other species; it may however be distinguished by its 
general habit, by the form and character of the pedicellarie, and by the posture and 
character of the armature of the adambulacral plates. Neither of the three forms above 
referred to could possibly be mistaken for Pedicellaster scaber. 
Family AsTERIID a, Gray, 1840, emend. 
The investigations of the last decade have resulted in the establishment of more 
definite morphological limits for this cosmopolitan family than were formerly recognised, 
and the removal of several genera whose plan of structure is essentially different. 
The genera now classed together in the family Asteriide constitute a well-defined 
group, the alliance of which is natural and self-evident. They are enumerated in the 
following table. 
Synopsis of the Genera included in the Family AsTERUDz. 
A. Abactinal skeleton well developed. 
a, Abactinal skeleton reticulate. 
a. Abactinal plates bearing definite spines . i : ¢ : : Asterias. 
6, Abactinal plates bearing large spherical tubercles. Uniophora. 
b, Abactinal skeleton composed of broad imbricating plates, cored ra thick 
membrane masking the plates and their appendages . 5 2 5 Calvasterias, 
B, Abactinal skeleton more or less aborted. 
a. Rays five. Form subpentagonal : ; ; : : : : . Anasterias. 
b. Rays numerous and elongate. c : : : c 2 . : Pycnopodia. 
Genus Asterias, Linné. 
Asterias (pars), Linné, Systema Nature, 1766, ed. xii. p. 1098. 
Stellonia (pars), Nardo, De Asteriis, Oken’s Isis, 1834, p. 716. 
Uraster (Agassiz), Forbes, Mem. Wern. Soc. 1839, vol. viii. p. 114. 
Asteracanthion (pars), Miiller and Troschel, Monatsb. d. k. preuss. Akad. d. Wiss. Berlin, April 1840, 
p. 102. 
Leptasterias, Verrill, Proc. Boston Soc. Nat. Hist., 1866, vol. x. p. 350. 
Coscinasterias, Verrill, Trans. Conn. Acad. Arts and Sci., 1871 (1867), vol. i. part 2, p. 248. 
Margaraster, Hutton, Cat. Echin. New Zealand, 1872, p. 4 (non Margaraster, Gray). 
Marthasterias, caliens Bull. Soc. Zool. pees 1878, p. 141. 
a Doubt ie ton Sercronn ip Drs. Danielssen and ioe (Nyt ap. ip Nabe pipe Bd. xxvii. p. 270; ; 
Den Norske Nordhavs-Expedition, 1876-1878, Zoologi, xi. Asteroidea, Christiania, 1884, p. 39) as to the validity 
of this species, which they consider to be identical with Pedicellaster typicus. The arguments drawn from certain 
points of structure, which they state were insufficiently described by Sars, strongly support that view ; never- 
theless, whilst acknowledging the cogency of the facts adduced by my learned colleagues and with full respect 
for their judgment, I venture to retain the species, at least for the present, as, after the examination of further 
specimens referred to Pedicellaster typicus, I am still inclined to believe that the two forms are distinct. I 
hope, on a future occasion, to be able to compare them side by side and finally settle the question. 
