132 



THE AMERICAN NATURALIST 



[Vol. XLI 



The population of Tripoli, according to the latest official data,* 

 amounts to 711,242. Among this are 16,670 Jews. The most south- 

 ern point at which the latter are found is Orfella. They live an ex- 

 tremely miserable life and in places suffer even partial slavery. They 

 do not emigrate because they know not where to go. 



A. H. 



ZOOLOGY 



Dean's Chimaeroid Fishes ^ is one of the most strikingly illustrated 

 works yet issued by the Carnegie Institution. Any adequate sum- 

 mary of its contents is impossible here; all that can be attempted is 

 an enumeration of its contents. For several years Dr. Dean has 

 labored indefatigably in obtaining embryos of this group of rare 

 Selachians. The work is based on the eggs of the Pacific Chimcera 

 collei, the eggs of which were obtained from the gravid females and then 

 incubated in floating boxes, but unfortunately these often broke adrift 

 and about 150 eggs have been lost in this way. 



After an introductory chapter on methods and the like Dr. Dean 

 first describes the appearance, habits, etc. , of the fish and then proceeds 

 to a study of the development. The egg-capsule is beautifully figured 

 and described in detail, this part of the work being made more valuable 

 by figures of the egg-capsules of other chimseroids, both recent and 

 fossil. The egg is fertilized before oviposition and Dr. Dean was 

 fortunate enough to get specimens showing various phases of the proc- 

 ess of fusion of the male and female pronuclei. Polyspemy is appar- 

 ently the usual condition. The segmentation is in general of the usual 

 Selachian discoidal type but is accompanied by a fragmentation of 

 the yolk. A single early stage of gastrulation is described in detail, the 

 striking feature being that the blastopore is not, as in other clasino- 

 branchs, at the edge of the blastoderm but inside its rim, a (ondition 

 which throws much light on gastrulation in other forms, eoneiusioiis 

 which are supported by two other stag€\s. 



• M6hier de Mathuisieulx, L'Anthropologie, XVII, 1906, Nos. 1-2, pp. 237- 



2 Dean, Bashford: Chimseroid Fishes and their development. Carnegie 

 Institution, Publication 32, Washington, 1906, pp. 194, 11 plates. 



