202 NATURAL SCIENCE [March 



Trochelminthes. In the account of the Nemertines no reference is 

 made to the important difference in the position of the nerve cords 

 with respect to the musculature in the various orders, that was pointed 

 out long ago by Hubrecht. Balanoglossus, Ccplialodiscus, and 

 Bhabdopleitra are placed, but with some hesitation, with the Chordata. 



Amongst the novelties of the book may be mentioned the number 

 of fossil vertebrates described and figured, the amount of embryology 

 of each type, and the phylogenetic trees at the end of each Phylum, 

 No doubt the last have their use, but one or two of them do not 

 appear to agree with the text. Thus, on p. 483 of vol. i., the tree 

 representing the Annulata, shows a ' chaetopod ' stem rising from the 

 Archiannelida, and ultimately bifurcating into Oligochaeta and 

 Polychaeta. This is all right, but the Gephyrea and Hirudinea are 

 seen issuing, one on each side, from this common stem. This does not in- 

 dicate the, probably, true course of events, nor, indeed, does it agree with 

 the statement that " the Hirudinea diverge somewhat widely from the 

 Chaetopoda, but a study of their earlier developmental stages shows 

 unmistakably their close connection with the latter group, more 

 particularly with the Oligochaeta." 



There can be little doubt but that the Leeches are degenerate 

 Oligochaeta — for have we not a Leech with bristles ? — and they should 

 therefore have been represented as springing from that class and not 

 from the common stem. The armed ' Gephyrea,' too, can l)e traced 

 step by step to the Polychaeta. 



The description of many of the examples will be found very 

 useful, some because of their novelty as types, others as being local 

 forms. Thus, Triton iiodifcrus represents the Gastropoda, instead of 

 the snail; Anthenea stands for Asterias; ChiloscyUiun fuscum 

 replaces Scylliwn canicula. 



The anatomical account of A^ms and of HormiijJiora will lie 

 welcome, and especially interesting is that of Ccdlorliynchus. But 

 some of these descriptions lose in value owing to errors, both of com- 

 mission and omission. The figure of the transverse section of 

 Nereis is wrong in the limitation of the coelom ; there is no mention 

 of the ' ciliated organ ' which was discovered and described by 

 Goodrich in 1893, and is now known to be of considerable morpho- 

 logical importance. The authors clearly recognise that the Polychaete 

 nephridium, or ' diplo-nephridium,' differs from that of the Oligochaete, 

 which is an ' ectonephridium.' Goodrich's observations have a direct 

 bearing on this distinction. 



Is it true that " in Nereis dumerilii there is only a single pair of 

 testes, situated in one of the segments between the i 9th and 25th ? " 

 If it is (and we doubt it) it is so exceptional a limitation amongst the 

 Polychaeta that it should be specially nnrntioned as such. 



In the account of Cucumerina, we meet with the astounding state- 

 ment (p. o72) that in the respiratory trees, "each of the terminal 

 branches ends in a ciliated funnel opening into the coelome." Is 

 there, here, a confusion with the sessile, ciliated cups (without ex- 

 ternal outlet) of Chirodota and Synapta? or with tlie posterior 

 nephridia of Echinids ? On p. 439, as well as in the account of the 

 earthworm, the nephridial funnel is said to open into the coelune in 

 the segment " corresponding to " the external pore. Surely everyone 



