134 



Report on Zoology. 



titled, The Invertebrata of Massachusetts, written by the 

 late Dr. A. A. Gould and now edited by J. A. Binney. The 

 volume contains chiefly descriptions of the species of mol- 

 lusca found on the coast of that state. It contains over 400 

 wood cuts from drawings by Prof. E. S. Morse and litho- 

 graphic plates on which are 136 additional figures. The 

 former edition of the work contained, in addition to the mol- 

 lusca, descriptions of the Crustacea, annelida and radiata, but 

 owing to the imperfection in Dr. Gould's manuscript at the 

 time of his death, these are not included in the present 

 edition. 



A Guide to the Study of Insects by A. S. Packard, Jr., 

 M. D. s was issued in the latter part of 1869. It is an octavo 

 volume of 700 pages, with figures illustrating over 1,200 ob- 

 jects. It cannot fail of proving a valuable aid in entomo- 

 logical studies. 



At the meeting of the American Association for the Ad- 

 vancement of Science, held at Troy, a number of valuable, 

 and interesting papers on zoology were read. Among these, 

 one by Dr. A. S. Packard, Jr., on the " embryology of Limu- 

 luspolyphemus, " which has some points of special interest to 

 zoologists, as throwing light upon the probable nature and 

 organism of the extinct forms of Crustacea known as 

 Trilobites. The embryo of the Limulus presents many 

 trilobitic features in its earlier stages, in some of which it 

 so nearly resembles certain genera of these fossil forms that 

 a figure of it might easily be mistaken for that of a Trilobite. 



He describes minutely the different stages in the de- 

 velopment of the embryo and shows the segmentation, 

 the appearance of the tubercles representing the first pair 

 of limbs, the stage in which the edge of the body is marked 

 out, and the stage in which the segments of the cephalothorax 

 are indicated, and the legs are of the full length, and then 

 the appearance of the nine segments of the abdomen, at 

 which time the shell of the egg bursts and the young animal 



