Miscellaneous. 263 



of the United States are hermaphrodite and viviparous. Specimens 

 from the coast of Oregon and Washington show that the same 

 condition exists in the reproductive follicles as in those of Ostrea 

 edulis of Europe. The presence of eggs and of spermatoblasts and 

 spermatozoa in the same follicles is the invariable rule. The ova, like 

 those of 0. edulis, are much larger than those of 0. virginica, though 

 perhaps not quite so large as the former. The embryos are 

 fertilized in the gill and mantle cavities, where they undergo 

 development. 



These north-west-coast oysters also resemble the oysters of Europe 

 in that they are small and have little or no indication of purple 

 pigment on the impression or point of insertion of the adductor 

 muscle, which is so conspicuous a feature in Ostva virginica of our 

 eastern coast. — Proc. Acad. Nat. Sci. Philad. Nov. 15, 1892. 



Lay^ge Variations in the Metamorphosis of the same Species. 



An elaborate memoir entitled, "The Embryology and Metamorpho- 

 sis of the Macroura," by W. K. Brooks and F. H. Herrick, makes 140 

 pages quarto of the fifth volume of the Memoirs of the U. S. National 

 Academy of Sciences, and is illustrated by 57 plates. The species 

 microscopically investigated and here reported upon are of the genera 

 Oonodactylus, Alpheus, and Stenopus. The authors mention, in the 

 introductory pages, as one remarkable result of their study of the 

 genus Alp)heus, the discovery that while the larval stages of different 

 species are similar, the individuals of a single species sometimes 

 differ more from each other as regards their metamorphoses than 

 the individuals of two very distinct species, and make on this point 

 the following remarks : — 



This phenomenon has been observed by us and carefully studied 

 in two species — Alpheus Jieterochelis and Alpheus Saxdcyi — and it is 

 described in detail, with ample illustrations, in the chapter on the 

 metamorphosis of Alpheus. In the case of the first species the 

 difference seems to be geographical, for while all the individuals 

 which live in the same locality pass through the same series of 

 larval stages, the life-history of those which are found at Key 

 West is very different from that of those which live on the coast of 

 North Carolina, while those which we studied in the Bahama Islands 

 present still another life-history. In the case of the second species 

 — Alphexis Saulcyi — the difference stands in direct relation to the 

 conditions of life. The individuals of this species inhabit the tubes 

 and chambers of two species of sponges which are often found 

 growing on the same reef, and the metamorphosis of those which 

 live in one of these sponges is sometimes different from that of those 

 which inhabit the other. In this species the adults also are 

 different from each other, but as we found a perfect series of 

 transitional forms there is no good reason for regarding them as 

 specifically distinct ; and in the case of the other species — Alpheus 

 heterochelis — we wore unable, after the most thorough and minute 

 comparison, to find any difference whatever between adults from 

 North Carolina and those from the Bahama Islands, although their 



