I04 ECHINOIDEA. II. 



siiice Olie is known onl>' from the Northern Atlantic, the otlier oiily from tlie Malay Arcliipelago and 

 Japan, it mav be well to keep the Pacific form as a Var. gibhosiis. for the present, though it seems 

 to be distinguished almost alone by the character of its geographical distribution. 



Tlie other species from the Challenger», Haiiiastcr zonatus. is so very imperfectly described 

 tliat it is impossible to found npoii that description any definite opinion of its claim to form a separate 

 species. The fignres, to be sure, show it clad in a close and uniform coat of sjsines; but also in 

 H. cxprrgifiis the coat of spines may be ratlier close — and in the description of //. Moifzi (;Blake»- 

 Echini. p. 66) the tnberculation of H. zonahis is stated to be more distant, as it is in //. cxpergitus. 

 It is thns, evidently, no very reliable character. The large fasciole and the deep anal groove do not 

 seem ver}' reliable characters either, as it may be almost exactly similar in cxpergitus, so that it does 

 not seem very improbable, when Agassiz thinks the differences from cxpergitus may be dne oiih' to 

 age. On examining the type-specimens in the British Mnsenm, I get the following resnlt. The specimen 

 from St. 8, off Gomera, Canaries, is undonbtedly //. cxpergitus, with which species it also agrees 

 exacth' in the pedicellariæ; bnt the specimen from St. 126 (off Rio Janeiro, 750 fm.s.) is nndoiibtedly 

 something qnite different. Unfortunately the specimen is completeh- crushed, only the apical and the 

 actinal regions being tolerably preserved. As regards the strncture of the test, it may be pointed out that 

 the labrum does not reach the second adjoining ambulacral piates. There are only two genital openings 

 and the apical system is not ethmophract as in Hemiastcr ; the madreporic plate extends backwards 

 and separates the posterior ocular piates, but is not prolonged into the posterior interambulacrum. 

 The peripetalous fasciole is more Schizastcr-\\Vit^ not rouud as in the figured specimen, and it is not 

 so broad as in that figure; any trace of a latero-anal fasciole caimot be seen — but that is no definite 

 proof of its non-existence, 011 accouiit of the poor coudition of the specimen. For the rest the specimen 

 is abnormal, the right anterior petal lacking; the left side is normal, showing the posterior petal only 

 one third the length of the anterior petal. The spines are simph- widened towards the point, not of 

 the elegant shape of those of Hemiastcr. The globiferous pedicellariæ are very different from those of 

 H. expergitus; the valves (PI. XV. Figs. 3, 7) enclose a large (probably glandular) space, which opens 

 with a small pore at the base of the single, compressed tooth, which terminates the long and slender, 

 curved blade — a strncture exactly similar to that fonnd in Scliizaster fragilis a. o. (comp. below, p. no). 

 The tridentate pedicellariæ are like those of cxpergitus . but only the small form was fonnd; the 

 rostrate pedicellariæ (PI. XV. Fig. 11) differ somewhat from those of cxpergitus, as seen by a comparison 

 of the fignres. That the spicules of the tube-feet are few in numbers can scarcely mean anything as 

 a distinguishing character, since there is considerable variation in this respect in expergitus. 



Ouite recently Professor Doderlein (Echinoidea d. deutsch. Tiefsee-Exp. p. 247) has referred 

 with soine doubt a specimen from the Rockall-Bank to Hevtiaster zonatus. and probably he is quite 

 right herein, judging from his fignres and description of the pedicellariæ. The globiferous pedicellariæ 

 are seen to agree with those figured here from the type specimen; the single difference, aswellingon 

 the stalk, which I have not found in the type specimen, can scarcely be of any importance. More 

 different are the rostrate pedicellariæ — but as in expergitus these pedicellariæ differ rather mucli in 

 form, the difference herein can scarcely necessitate a separation. Unfortunately also Professor Doder- 

 lein' s .specimen was quite crushed, so that we must still remain ignorant of the structure and form 



