157 



that an isolated ray , even tho it be severed from the starfish at some 

 distance from the disk, does under normal conditions develop a com- 

 plete, new individual from its jDroximal end. Unfortunately Miss Monk 's 

 papers (1903, 1904, Proc. Philadelphia Acad. Nat. Sci. vol. 55, p. 351 

 and vol. 56, pp. 596 — 600) are handicapped by the fact that her star- 

 fishes were wrongly identified (see Fisher, 1911, Bull. U.S. Nat. Mus., 

 no. 76, pp. 242, 243) as is easily seen from her figures, and the title of 

 her principal paper ^"Variability and Autotomy oi Phataria") is con- 

 sequently quite misleading. Phataria is an entirely different starfish 

 from the one with which she was concerned and so far as we have any 

 evidence its powers of regeneration are quite limited, and there is no 

 evidence at all that it is autotomous. But no doubt for years to come 

 we shall find references in the literature to the remarkable regenerative 

 powers of "P/^aiarm"! As Fisher has pointed out, the starfish with 

 which Miss Monks worked, was Linckia columhiae Gray. It is a typical 

 member of the genus and closely related to the West-Indian species L. 

 guildingii Gray. 



Nowhere in her papers does Miss Monks discuss the possible use to 

 the starfish of autotomy, but she demonstrates perfectly that it is a nor- 

 mal and not an abnormal phenomenon and that it takes place in response 

 to internal stimuli which are not evidently associated with any changes 

 in the environment. The only writer , so far as I can learn , who has 

 referred to the use of autotomy in starfishes, is Ritter, who suggests 

 that it may be an asexual method of reproduction in Linckia (1902, 

 Science, N.S., vol. 15, p. 62), a conclusion which this brief paper is in- 

 tended to support. 



While enjoying the privileges of the Marine Laboratory of the 

 Carnegie Institution of Washington, at Montego Bay, Jamaica, in Fe- 

 bruary and March, 191 2, thanks to the kindness of the Director, Dr. A. 

 G. Mayer, I took occasion to collect and preserve all the specimens of 

 Linckia guildingii Gray which could be found. In all, 93 specimens 

 were secured. Of these only three are symmetrical; two have five rays, 

 in one case about 15 mm long, in the other about 23, and one has six 

 rays each 14 mm in length. In the six-rayed specimen and in the larger 

 five-rayed, the rays are slender, the diameter of each ray being only 

 about .14 of its length; in the smaller five-rayed specimen, the dia- 

 meter of the rays is about .27 of their length. 



Of the remaining 90 specimens, 13 (or 14 per cent] are isolated arms 

 the proximal ends of which have healed, but no new rays are as yet 

 visible. There are 16 (or 18 per cent) isolated rays, at the proximal 

 ends of which new rays less than 5 mm in length have formed ; in one 

 case there are six new rays, in twelve cases there are five, and in three 



