342 



SCIENCE 



[N. S. Vol. XLII. No. 1080 



India. One of these Indian species of Dry- 

 opithecus (D. punjabicus) is apparently re- 

 lated to the gorilla; another (D. giganteus), 

 perhaps to the chimpanzee; an allied genus, 

 Palososimia, bears a significant resemblance to 

 the orang; a fourth type, Palmopithecus siva- 

 lensis Lydekker, is a synthetic form with re- 

 semblances to the gorilla, chimpanzee and gib- 

 bon. In the reviewer's opinion all these are 

 more primitive than any of their modem 

 relatives and indicate that in the Upper Mio- 

 cene northern India was not far from the 

 center of evolution of the anthropoids and 

 m.an. 



The important genus and species Sivapithe- 

 cus indicus, from the Lower and Middle 

 Siwaliks, rests upon fragments of the lower 

 jaw and dentition. From these Dr. Pilgrim 

 has attempted a restoration of the lower jaw 

 that shows a subhuman divergence of the op- 

 posite rami and a very short, man-like sjrm- 

 physis. Pilgrim regards this genus as in or 

 near the ancestral line of Homo sapiens. 



The reviewer regrets to report that after a 

 careful study of the evidence he believes Dr. 

 Pilgrim has erred in attributing the above- 

 mentioned human characteristics to Sivapithe- 

 cus, the jaw of which, in the reviewer's 

 opinion, should be restored rather after the 

 pattern of the female orang jaw. The evi- 

 dence for this conclusion will be given else- 

 where. The reviewer would also dissent from 

 Dr. Pilgrim's allocation of Sivapithecus to the 

 Hominidae, preferring to place it by definition 

 in the Simiidffi, since it had ape-like canines 

 and front premolars, and, as the reviewer inter- 

 prets the evidence, also an ape-like symphysis. 

 William K. Gregory 



castle and wright on crossing over in rats 

 In a recent number of Science (August 6) 

 Castle and Wright describe a case of linkage 

 in rats. One point of general interest indi- 

 cated by their results is not pointed out by 

 these authors ; namely, that crossing over occurs 

 in both sexes. This conclusion depends on the 

 appearance, in F, of their cross (red-eyed 

 yellow by pink-eyed yellow), of doubly recessive 

 rats. They state that two such rats appeared. 



this being inferred -from the fact that two of 

 the F„ pink-eyed yellows, when mated to red- 

 eyed yeUows of stock, " produced only red-eyed 

 (yellow) oiispring." This result must mean 

 either that these two rats were not sufficiently 

 tested, and were not really double recessives; 

 or else, if they were double recessives, that 

 there had been crossing over in both sexes of 

 Fj rats. As to the first possibility, the crucial 

 point is the number of red-eyed offspring pro- 

 duced in the test mating. Unless this number 

 was large enough to completely rule out the 

 possibility of the F^ pink-eyed rats having been 

 only heterozygous for the red-eye factor, the 

 second alternative is not necessarily true. li 

 the second possibility be true it follows that 

 the relation of crossing over to sex determina- 

 tion is different here from that in Drosophila 

 (Morgan) and the silkworm moth (Tanaka), 

 where no crossing over occurs in the sex which 

 is heterozygous for the sex factors^^ (male in 

 Drosophila, female in the silkworm moth). 

 Since the evidence from sex-linkage and cytol- 

 ogy shows that in several mammals (man, cat, 

 etc.) the male is heterozygous for the sex 

 factor, we should expect, if the relation to 

 crossing over is a general one, that no crossing 

 over would take place in the male mammal. 

 A. H. Sturtevant 

 August, 1915 



SCIENTIFIC BOOKS 

 A Monograph of the Existing Orinoids. Vol- 

 ume 1. The Comatulids :F art 1. By Austin 

 Hobart Clark, Assistant Curator, Division 

 of Marine Invertebrates, United States Na- 

 tional Museum. Bulletin 82. Washington, 

 Government Printing Office. 1915. 4to. 

 Pp. vi + 486 ; with -613 text-figures, and 17 

 plates. 



The last general treatise upon the Eecent 

 Crinoids is contained in the monumental 

 volumes of P. Herbert Carpenter upon the 

 " Stalked Crinoids and the Comatulse," pub- 

 lished in 1884 and 1888 by the British gov- 

 ernment as part of the results of the voyage of 

 H. M. S. Challenger. Although based chiefly 

 1 See Sturtevant, A. H., Amer. Nat., XLIX., 

 1915. 



