54 NATURAL SCIENCE [January 



their biology and general anatomy, he proceeds to give a comparative 

 review of the different organs, or systems of organs, in turn, followed 

 by a very clear account of the three types of development, and con- 

 cluding with a few pages on the systematic arrangement of the group 

 and its relation to other groups, especially to the Turbellaria. It is, 

 however, to be regretted that, in his anatomical part, he employs the 

 term " coelome " to designate what has no more morphological than it 

 has etymological right to the name, and without even attempting to 

 jvistify his use of it, or perceiving that it is necessary so to do. There 

 are also a few apparent discrepancies in his descriptions, arising from 

 the fact that, while he admits Burger's classification to be the more 

 natural, and adopts it finally in the systematic part, he uses Hu- 

 brecht's names for the " sections " throughout the anatomical part, 

 and does not seem always to remember that they do not connote 

 the same thing as the names used by Burger. It would have been 

 clearer, as well as more consistent, to have used throughout the same 

 classification. 



Most of the figures are diagrammatic, and it is, we think, unfortunate 



that so many of these are of the composite type. Not only are such 



figures misleading, since they represent structures side by side which 



do not so occur in nature (as, for instance, in the section of the 



epidermis on p. 11), but also it is very difficult to make them strictly 



accurate. Thus, by representing in one diagram the proboscis of a 



nemertine invaginated on one side and evaginated on the other, the 



impression is produced that evagination is due rather to the drawing 



back of the proboscis-sheath than to the pushing out of the walls of 



the proboscis itself, since this organ is no further forward in the one 



case than in the other, while its junction with its sheath is further 



back on the evaginated side. Again, one would gather from Fig. 18 



the erroneous impression that the vascular system of Carinella ended 



posteriorly in the same way as that of Carinoma, also that all 



species of Carinoma had the two blindly-ending longitudinal vessels 



anteriorly that are there represented ; and from Fig. 21, since nothing 



to the contrary is stated in the text, that the excretory system of 



Amphiporus, and of all species of the genus, communicates with the 



exterior by five pairs of ducts, whereas Oudemans, from whom, as we 



are told, the diagram is taken, not only expressly states that in some 



species there are but two ducts, but also that in the particular species 



to which the diagram refers the number is not even the same on the 



two sides of the body. Prof. Joubin, as it happens, represents on 



the right side what Oudemans made out to be the arrangement of the 



excretory system on the left. 



It would also have been an advantage to the reader if the same 

 reference letters had been used for the same structure in all the 

 figures, and if the text and figures had harmonised better with one 

 another. One does not know, for instance, whether one is to believe 

 the text or the figure with regard to the position of the deep glands 

 of the Schizonemertines (p. 12 and Fig. 7b), or with regard to the 

 position of the nerve-cord in Cephalothrix (p. 29 and Fig. 7a) ; and 

 it is also somewhat confusing to find that in the description of the 

 characteristic features of the proboscis of the Unarmed nemertines 

 (p. ] 6), the figure of a papilla in an Armed one is referred to, while it 



