ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 201 



The material included the forms taken by most of the scientific expe- 

 ditions, European and American, and the observations were supple- 

 mented by the study of living animals at Djibouti. In regard to 

 affinities, perhaps one of the most interesting points is the existence of 

 numerous structural characters showing resemblance to the Reptant 

 Crustacea. The author emphasises the fact that these are to be regarded 

 as an example of " adaptive convergence," and in no way as indications 

 of affinity. There is clear evidence that the Alpheidae are to be re- 

 garded as Natantia, and that among the Natantia they belong to the 

 Eucyphota, being specially related to the Hippolytidae. Nevertheless, 

 in several respects they show direct relations to the Schizopods, thus 

 affording evidence against Boas' view that all the Eucyphota are derived 

 from a form resembling Penseus. The author is disposed to believe that 

 the Penaaidae and Eucyphota have arisen independently from Schizopoda. 

 The author's personal investigations in the Red Sea resulted in a 

 collection including 500 specimens, belonging to some forty species, 

 whose habits are described in careful detail. 



North American Astaeidae.* — Mr. W. P. Hay gives a synopsis of 

 the 79 North American species and sub-species now recognised in the 

 genus Cambarus, and the live known species of Astacus. In a first list 

 the natural groups are given with their distinctive characters and with 

 indications as to their distribution. The second list is a purely artificial 

 key for purposes of identification. 



New Argulidae.t — Dr. J. Thiele describes Ghonopeltis inermis 

 g. et sp. n., which differs from the two known genera Dolops Audouin 

 ( = Gyropelfis Heller) and Argulus Mull, in the entire absence of the first 

 antennae. The specimen came from the branchial cavity of a species of 

 Chromis. Three new species of Argulus are also noted. 



Development of Penilia schmackeri Richard.! — Mervin T. Sudler 

 obtained a large amount , of Crustacean material in the harbour of 

 Beaufort, N.C., in June 1896, which proved to consist entirely of this 

 species. The animals appeared suddenly, and after occurring in large 

 swarms at the surface of the water for a few days, as suddenly dis- 

 appeared. No males were found, but the brood-chambers of the females 

 were filled with developing eggs. The eggs contain little yolk, and the 

 author believes that each egg is the result of the fusion of four ovarian 

 cells. No trace of a polar body was observed. Segmentation is total, 

 and the first cleavage is transverse. Of the resultant two cells, the 

 anterior appears to form the anterior region of the future embryo, and 

 the posterior its posterior region. There was no indication of the early 

 differentiation of genital cells described by Grobben for Moina. Gastru- 

 lation occurs by inwandering. In regard to the order of appearance of 

 the appendages, Penilia differs from most Crustacea in that the second 

 antennae appear before the first, the latter being often late in develop- 

 ment. 



Antennal Glands of Lobster.§ — Mr. F. C. Waite has investigated 

 the structure and development f these organs in Homarus americanus 



* Amer. Nat., xxxiii. (1899) pp. 957-66 (1 fig.). 



t Zool. Anzeig., xxiii. (1900) pp. 46-8. 



t Pro<\ Bostou Soc Nat. Hist., xxix. U899) PP- 109-31 (3 pis.). 



§ Bull. Mus. Comp. Zool. Harvard, xxxv. (1899) pp. 151-210 (6 pis.). 



April 18th, 1900 P 



