304 NATURAL SCIENCE. Oct., 



mongooses. In the sixth part are fossil hyaenas, dogs, and foxes ; in 

 the seventh, bears, raccoons, and weasels ; in the eighth, seals and 

 their kind, and we are introduced to the oxen, which continue in 

 part 9, and are succeeded by the sheep, goats, and antelopes. 

 Part lo carries us well into the deer. Mr. Lydekker's descriptions- 

 are distinctively and pleasantly written, and much interesting and 

 anecdotal matter is incorporated. Special attention too has been 

 paid to the occurrence of each form, when known, in the fossil state. 

 Taken as a whole, we do not know of any work that may be sO' 

 satisfactorily recommended to those who wish an acquaintance with 

 the mammalia. An additional interest will be found in the living 

 animals at the Zoological Gardens if studied family by family by the 

 aid of Mr. Lydekker's Natural History. 



Limpets and their Allies. 



Studien iJBER DocoGLossE UND Rhipidoglosse Prosobranchier nebst bemer- 

 kungen iiber die phyletischen Beziehungender Mollusken untereinander. By 

 Dr. B. Haller. 4to. Pp. iv., 173; 12 plates, coloured. Leipzig: Engelmann,. 

 1894. 



The greater part of this interesting and most important work is taken 

 up with the description of the anatomy and morphology of the Doco- 

 glossa, or Limpets, and the Rhipidoglossa, or group to which the Key- 

 hole-Limpets, the Ormers, and the Topshells belong. The Docoglossa 

 are divided by the author into Bibranchia, comprising the two-gilled 

 Propilidium, Monobranchia, or those with the single neck gill, and the: 

 Cyclobranchia, or those, like the common Limpet, which have a 

 circlet of gills. Where the Lepetidae, which have neither the neck- 

 gill nor gill-circlet, come in is not apparent. Of these three groups^, 

 the first named is considered to be the oldest, the others following in 

 their order. Of the Rhipidoglossa, the genus Plenrotoniaria is held to 

 be the oldest, though Dr. Haller speaks of its anatomy being quite 

 unknown, having apparently entirely overlooked Dall's account of it 

 in the Bulletin of the Museum of Comparative Zoology at Harvard 

 College, xviii. (i88g), pp. 397-403, a circumstance not altogether to- 

 be wondered at considering the way in which the eminent American 

 naturalist buries his best results in papers whose titles give no clue to- 

 their valuable contents. 



Dr. Haller's last twenty pages are, however, the most interesting 

 from a general point of view, containing as they do his conclusions- 

 concerning the phylogenetic relations of the various members of the 

 MoUuscan stem. These conclusions are of great importance, and 

 will be best made clear by reproducing his own diagram. 



On contrasting this with the tree drawn up by Pelseneer (Natural. 

 Science, iii., p. 37), which is now very widely accepted, certain pro- 

 minent differences, apart from mode of drawing up, become 

 apparent. Thus, to begin with. Dr. Haller takes the Chitons as his 

 base, and derives all the others from it, including the Cephalopoda, 

 although both their embryology and geological history are against 

 such a supposition. Other equally startling conclusions, such as the 

 classing of the Pteropoda with the Pulmonata, the sea-butterflies 

 with land-snails, may be observed, and further comments can be 

 safely left to the reader. Whether Dr. Haller's tree will come un- 

 scathed through the fire of criticism is doubtful, but every thoughtful 

 attempt to unravel the genetic relationships of a group is of extreme 

 value, and we are proportionately grateful to the author for this 

 latest contribution to MoUuscan literature. 



