3G s. goto: 



tliis appeal's to be tlie only form witli wliich a direct comparison can be 

 institntiîd. The description is too short to render any assistance in this case." 



In his paper of 1894 Vermt^l makes some important critical remarks 

 on this si>ecies, putting do\\n PararcJiaster semisquamoMs var. occidentalis 

 Si^VDEN and Pararclt. armrttvs Sladen as synonyms of his Bentho^yecten 

 spinosvs. He says ['94, p. 245] : 



" A comparison of a hxrge series of this species, of various sizes from 

 those that are 15 mm. up to large ones 260 mm. in diameter, shows that 

 the two foiins described by Sladen from off the Atlantic coast are probably 

 both identical Avitli that described by me. 



" This species varies considerably in several details of its structm'e, 

 according to its age. None of Sladen's specimens were full grown (largest 

 size given is 74 mm. in diameter). Moreover there is often considerable 

 variation in specimens of the same size and from the same locality, in the 

 size of the disk, number, size, and arrangement of the spines on the 

 marginal ])lat(3S, etc. Some few examples have the disk at least one-third 

 broader than others having the same length of rays, and such specimens 

 naturally liave large inferior interradial areas, with the plates more nimierous 

 than usual, as many as twenty to twenty-five being present in some cases. 

 The j)apida3 often extend out on the rays, in large examples, as far as the 

 fifth pair of marginal plates ; they cease sooner in the median line than to 

 either side of it. They are often j^i'esent on the central area of the disk, 

 among the large primary spines. The actinal and adambulacral spines on 

 the largest specimens are more numerous and longer than Sladen's descrip- 

 tions indicate, but the half-gi-own specimens agree well with his examples, 

 in most respects. 



" The pectinate pedicellariao described by Sladen as characteristic of P. 

 armatvs are commonly lacking entirely on our specimens, or exist only in 

 veiy small numbers. The dorsal plates of the rays are rounded and ovate, 

 unequal, and most commonl}- isolated in the integument. They usually bear 

 only a single, small, slender, acute spine, rarely two. The large disk-spines 

 are variable in number and length, but they are always restricted to the 

 central area of the disk, and the largest are borne on the primär}^ x^l^^^s. 



