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Show 1881.] THE SURVEY OF H.M.S. ' ALERT.' 97 simply grooved, and not fringed with spines; it is situated not far from the centre of the disk. 22=36, r = 1 3 ; the arms are 7"5 millims. wide at the point where they become free from the disk, and 4 millims. at their tip ; the adambulacral spines do not exceed 2 millims. in length ; the interbrachial angles vary very greatly. One specimen taken, at 30 fathoms, inTrinidad Channel. ASTERINA FIMBRIATA, Perrier, Rev. des Stell. 1875, p. 307. One small specimen, from Cockle Cove, and two still smaller, from Sandy Point, are, with some hesitation, referred to this species. I have not seen M . Perrier's type ; and the variation exhibited by the species of this genus at various periods of their lives makes it impossible to speak definitely unless one has in hand a considerable series '. ASTROPECTEN. Two dried specimens of a species of this genus were obtained at a depth of 48 fathoms, in lat. 32° 39' S., and long. 50° 11' W. They present a very remarkable resemblance to A. articulatus, Say, as figured by Agassiz (' North-American Starfishes,' pi. xix.) ; and the two specimens also differ in just the same way from one another as do two specimens mentioned by M . Perrier-in the fact, namely, that in one some of the dorsal plates are provided with spines, while from the other such spines are completely absent. The specimens also differ somewhat from one another in the number of dorsal marginal plates. The length of the greater radius of one specimen is 82 millims., and the number of plates 33 ; while in the other there are 38 plates, with a greater radius of 81 millims. In the case of both specimens the relation of the greater to the lesser radius is much the same, R being equal to about 5"75 r, the lesser radius in both specimens measuring 14 millims. Two large sword-shaped spines, with which a smaller third one is frequently associated, project upwards and forwards from the upper margin of the ventro-marginal plate ; they are sufficiently long for the first of each set to extend some way along the side of the dorso-marginal plate next but one in front of it ; extending inwards towards the ambulacral groove, the plates bear, in a somewhat irregularly double series, as many as seven well-developed spines in each set, and in addition to these there are a number of smaller spines and pedicellariae. From the middle of the arm the spines increase in size towards the angle, and diminish towards the apex. The spines on the adambulacral plates are with difficulty distinguishable : they are arranged in two rows ; and those of the inner series are the longer and stronger; there are generally three, more rarely only two, on each plate. 1 Since writing the above, another example of the same species has been received from Borja Bay, and I have also been able to see Prof. Perrier's valuable essay on the geographical distribution of the Asterida (Nouv. Arch. du Mus. 1878); from this I gather that he seems to be satisfied as to the presence of this species in the Chilian seas (cf. the remarks in the ' Revision,' p. 308). PROC. ZOOL. Soc-1881, No. VII. 7 |