HO BULLETIN 76, UNITED STATES NATIONAL MUSEUM 



I have given this extraordinary form subspecific rank in order to emphasize its 

 pecularities- structural, developmental, and geographic— and to free hexactis and 

 aequaHis from a further encumbrance of formae. 



lis range so far as known is restricted to the general region of the confluence of 

 the Strail of Georgia, Strait of Fuca, and Puget Sound. The large series which I 

 have examined was collected among the San Juan Islands, chiefly by Mrs. Ida Oldroyd. 



Its younger stages are different from those of aequalis in having fewer, more 

 widely spaced dorsal spinelets (arranged in pretty regular longiseries). Its structural 

 pecularities concern the wide range of its variations. These variations include a 

 few specimens which appear to be intermediate with L. hexactis f. regularis, which 

 occurs with rancouveri at the San Juan Islands. Other extermes are closely similar 

 to L. hexactis f. hexactis as noted below. 



In order to arrive at some semblance of order the specimens will be divided into 

 groups on the basis of the number of superomarginal spinelets. 



I. Superomarginal spinelets, four or five, rarely six, in a vertical series; a broad 

 conspicuous band of these combs extending along the dorsolateral curvature of the 

 ray (pi. 53, fig. 3); superomarginal plates broad and regular; inferomarginal spinelets 

 longer than superomarginal, slightly curved, two proximally and one or two distally; 

 a series of slightly longer actinal spines reaches far along ray while a second series 

 is usually present on the proximal third or half of ray. There is a definite channel 

 above the superomarginal spinelets and a narrow intermarginal one; in addition to 

 the dorsolateral papulae (see below) an intermarginal and two incomplete actinal 

 scries (largo examples). Adambulacral spines subcylindrical to subclavate, slender, 

 usually two at base of ray; then one and two, or one only. 



a 1 . Abactinal spinelets have the appearance of forming fairly regular longiseries (proximally two, 

 distally one) on either side of the regular carinal series. Spinelets short, typically robust, 

 cylindrical to subcapitate, round-tipped to subtruncate, coarser, more widely spaced and 

 fewer than in aequalis of the same size; dorsolateral spinelets one to three per plate, usually 

 two or three; carinal spinelets three to five; usually six discernible longiseries of abactinal 

 papulae. No small specimens. 

 6 1 . Carinals conspicuously broadened, nearly as wide as the dorsolateral area. Dorsolateral 

 plates very compact (one specimen only, R 60 mm., r 10 mm., br. 10.5 mm.) (PI. 53, 

 fig. 1.) 

 fc 2 . Carinals narrower than either dorsolateral area (pi. 53, figs. 2, 3) ; groups of dorsolateral 

 spinelets (not individual spinelets) in more or less distinct longiseries separated by long'- 

 series of papulae (six for abactinal area); rays moderately robust; 11 specimens from R 

 32 mm. to R 54 mm. (latter with R = 5.4 r). Type of vancouveri belongs here. 

 a 2 . Abactinal spinelets similar in numbers and form to o 1 but not arranged in longiseries of groups 

 or only very indefinitely; even the carinal series of groups may lose its distinctness; irregu- 

 larity largely due to papulae falling out of longiserial alignment; R 55 mm.; eight specimens, 

 three more or less intermediate with a 1 . (PI. 53. fig. 4.) 



II. Superomarginal spinelets averaging three; in some specimens being proxi- 

 mally four, distally three; or rather irregularly three or four; or three, with two 

 spines on a minority of the distal plates; or three distally and two irregularly on some 

 on the proximals; dorsolateral plates with one to three spinelets but more often one 

 or two; frequently only one inferomarginal spine. 



'i 1 . Abactinal spinelets arranged in fairly regular longiseries; six longiseries of papular areas in well 

 grown examples; carinal plates all rather narrow with three to five spinelets. Differing 



