118 BULLETIN 76, UNITED STATES NATIONAL MUSEUM 



lower side a few delicate, slender straight pedicellariae, others being present on the 

 plates themselves. The inner, shorter, spine is not involved in this web, which is 

 more prominent than in heteropaes, where it is with difficulty seen. 



The outstanding feature of the Hawaiian species, euplecta, is the presence of a 

 still wider actinolateral web, which involves also the basal half of the inner spine. 

 It is so tough that it has persisted in a specimen cleaned in potash. This web some- 

 times reaches nearly to the tip of the chisel-shaped spines, and sometimes is retracted, 

 leaving a third or even more of the spine free. When the spines are bent downward 

 the web is very conspicuous. The mouth angle is broad with one pair of contiguous 

 adambulacral plates behind the mouth plates, and the second pair well separated. 



Genus ASTROMETIS Fisher 



Aslrometis Fisher, A Preliminary Synopsis of the Asteriidae, etc., Ann. Mag. Nat. Hist., 



ser. 9, vol. 12, 1923, p. 254. Type, Aslerias serluli/era Xantus. 

 Marthasterias Verrill, Shallow-water Starfishes, 1914, p. 100. 

 Orthasterias Verrill, part, Shallow-water Starfishes, 1914, pp. 48, 175, 184. 



Diagnosis. — Coscinasteriinae resembling Sclerasterias but differing in having 

 large, spatulate, denticulate straight pedicellariae; outer inferomarginals without 

 trace of ventrolateral web; rays semicircular or heptagonal in section; dorsolateral 

 skeleton very irregular; the skeletal meshes not in two regular series on either side 

 of the carinal line of plates; dorsolateral spines developed in even tiny specimens; 

 they are numerous, in one or two irregular series on each side; adambulacral plates 

 diplacanthid proximally, monacanthid distally. Only the outer of the two infero- 

 marginal spines with cluster of crossed pedicellariae; superomarginal plates with 

 specialized pebbled area, the alternate plates spiniferous; actinal series of plates 

 incomplete, proximally spiniferous as a rule; first pair of postoral plates larger than 

 the second, in close contact; second pair in partial contact; crossed pedicellariae with 

 a conspicuously enlarged lateral tooth on outer side of terminal lip; not fissiparous. 



Remarks. — So far as observed, this genus has no immature fissiparous stage 

 such as is known for three species of Sclerasterias, nor is it fissiparous in the adult 

 phase as in the case of true Coscinasterias. 



The dorsolateral spines develop earlier than in the postfissiparous stage of Scler- 

 asterias. Even in specimens as small as R 13 mm., the dorsolateral series of spines 

 extends to the end of the ray (six dorsolateral spines to seven or eight carinals). 



In Sclerasterias the dorsolateral skeleton is somewhat like a set of rafters to a 

 roof. The carinal ridge is joined to the superomarginal "eaves" by fairly regular 

 transverse bars consisting of two elongate often terminally spatulate ossicles which 

 overlap about midway; over this joint the primary dorsolateral plates arise. Usually 

 before these develop, short longitudinal connectives appear along the line of the dorso- 

 lateral plates, dividing the "roof" into two regular longiseries of skeletal meshes or 

 intervals. (PI. 53, fig. 16.) 



In Astrometis, however, these transverse connectives are irregular in arrange- 

 ment and are made up of several pieces. The intervals are very unequal in size and 

 unsymmetrical in contour and arrangement. There is frequently only one large 

 mesh extending from the carinals to the superomarginals, followed by two; or two 



