REVIEWS AND BOOK NOTICES. 



373 



shell begins to form, and afterwards covers the whole trunk, but 

 not the head. 



The inner organs are developed from the inner germ-layer (en- 

 doderm), which divides into three leaves, one forming the middle 

 part of the intestine, and the two others the glands and ovaries. 

 The pharyngeal jaws arise as two small projections on the sides of 

 the primitive cavity. 



The male develops in the same mode as the female. The Roti- 

 fers, so far as can be judged from one species, seem to develop in a 

 manner quite unlike oilier worms, and in the earliest phases much 

 as in some Gastropods, the mode of their embryology not throwing 

 much light on the affinities of the group, which is of doubtful posi- 

 tion, though with more of the characters of worms than Crustacea. 



The young pass through a morula state, and the embryo directly 

 attains the mature form in the egg. 



BEVIEWS AND BOOK NOTICES. 



Sullivant's Icones Muscorum, op Figures and Descriptions 



have not tet been fioured. — Supplement {Posthumous) . With 

 eighty-one copper plates, imp. 8vo. Prefaced by a Biographical 

 Sketch of the author, by Asa Gray. Mr. Sullivant died on the 

 30th of April, 1873, leaving the plates of this exquisite volume 

 ready for publication, and the letter-press partially so. The 

 latter has been completed by his friend and associate, Mr. Les- 

 quereux ; and the volume has at length been brought out, at the 

 expense of Mr. Sullivant's executors, and in accordance with his 

 wishes. Only a very small edition has been printed. The deli- 

 cate copper plates were not intended for a large impression ; and 

 the number of botanists interested in the serious study of mosses 

 is supposed to be small. 



As with the larger first volume, with one hundred and twenty- 

 three plates, issued ten years ago, so with this supplementary one 

 now bequeathed to botanists, the sale of the whole edition, at the 

 price for the present fixed, would be far from covering the actual 



