1931] Abstracts and Reviews ,113 



gree conspicuous in the Beaufort area. Seventeen species are de- 

 scribed, most of them new. Of these the "Fishing Bank," a bank of 

 coralline nature with a West Indian fauna, to seaward of Beaufort In- 

 let, has yielded four. Collecting on the sea-beaches was incidental, 

 most material so collected being unfit for precise study. The bulk of 

 the sponges are harbor forms, at least eight sufficiently abundant to be 

 available for investigations of an experimental nature. The occur- 

 rence of a minute horny sponge of very simple character, designated 

 Pleraplysilla latens, is noteworthy, both because horny sponges as a 

 group inhabit more southern waters and because of the morphological 

 simplicity of the form. 



The families, subfamilies, and genera represented are defined, and 

 the paper may thus be used for purposes of identification. A con- 

 siderable amount of comparative data falling under the general head 

 of variation is recorded, and in the case of a number of the genera there 

 is discussion of the facts on which they rest. The illustrations, of en- 

 tire sponges and microscopic preparations, are for the most part photo- 

 graphic. 



Asymmetrical Regulation in Anuran Embryos with Spina bifida 

 Defect. By H. V. Wilson and Blackwell Markham. Journal Ex- 

 perimental Zoology, XXX. 1920. (Body of the paper accepted as a 

 thesis for the M. A. degree awarded to Blackwell Markham, 

 1918.) 



Abnormal embryos and larvae of the frog and toad are described, 

 the developmental processes in which add to our knowledge of what is 

 called the regulatory power of organisms. This is the power which 

 enables an organism, lower adult or embryo of higher form, to restore 

 or develop the typical form of body, after the destruction or amputa- 

 tion of a part of the whole, or after some interference in development 

 which blocks the normal course of differentiation. In the particular 

 cases described the normal backward growth of the axial structures of 

 the embryonic body, such as notochord and spinal cord, is prevented. 

 In a well-known type of embryo of this sort the tissue of the blastopore 

 lips, two stripes which diverge from the posterior end of the embryonic 

 body, becomes organized, each stripe forming a half spinal cord, half 

 notochord, etc., the half structures gradually coming together (process 

 of 'concrescence') in the median line to form a complete spinal cord, 

 complete notochord, etc. But in the embryos here described a dif- 

 ferent and asymmetrical kind of regulation is employed. Instead of 

 both streaks (blastopore lips) organizing and fusing, only one streak 



