of the Carboniferous Rochs of Scotland. 77 



of the Geological Survey, in 1905, he has resumed his study of the 

 subject, and has set forth the results in the elaborate monograph now 

 before us. It is based on the examination of upwards of 2,000 

 specimens, some of which are in an exceptionally fine state of 

 preservation, so that Dr. Peach has been able to recognize and 

 describe structures so delicate as the gills, and even, he believes, 

 the phosphorescent organs (photospheres) of certain species. Those 

 who have puzzled over the almost indecipherable fragments by which 

 these Crustacea are usually represented in the rocks will appreciate to 

 the full the patience and skill which Dr. Peach has devoted to their 

 interpretation, and will hesitate before they venture to dissent from 

 his conclusions. After due hesitation, however, some dissent must be 

 expressed. 



Forty-two species and varieties are described, of which twenty-three 

 are new, and they are referred to nine genera, of which four are here 

 established for the first time. Among the new genera the most 

 important perhaps is Tealliocaris, of which the abundant and wonder- 

 fully well-preserved material has enabled Dr. Peach to give a very 

 detailed account. 



Dr. Peach concludes that all the forms with which he deals are to 

 be, referred to the ' Schizopoda ', and not, as had been supposed in the 

 case of some of them, to the Decapoda. In doing so he makes no 

 reference to the more recent views on the classification of the 

 Malacostracous Crustacea, which are based on the work of Boas, 

 Hansen, and others. According to these authorities the * Schizopoda' 

 form a heterogeneous and unnatural group, comprising the more 

 primitive members of at least three widely divergent branches of the 

 Malacostracan stock. It is quite probable that these branches were 

 much less sharply differentiated in the Carboniferous period than they 

 are now, and the retention of the name ' Schizopoda ' as a convenient 

 term for the unspecialized ancestral forms which cannot be included 

 in any of the orders of living Malacostraca may perhaps be defended ; 

 but it seems to us that a consideration of the results of recent work on 

 this question suggests caution in accepting many of Dr. Peach's 

 conclusions. On one point at least there can hardly be any dispute ; 

 the characters assigned to several of the fossils make it quite imj^ossible 

 to refer them, as Dr. Peach does, to the families of existing Crustacea. 

 Thus, for example, the genera Anthracophausia and Crangopsis are 

 described as having the carapace loosely enveloping the thorax but 

 not coalescing with more than one or two of the anterior somites on 

 the dorsal side ; yet these genera are referred to the Euphausiidse, 

 in all the living forms of which, as in the Decapoda, the carapace 

 coalesces with the terga of all the thoracic somites. Ortmann has 

 already drawn attention to this character in. Crangopsis, and suggested 

 that the genus should be referred to the Mysidacea, or rather should 

 be regarded as intermediate between the existing members of that 

 order and the more primitive Malacostraca. If Dr. Peach's identi- 

 fication of the male sexual appendages on the first pleopods be correct, 

 Crangopsis would seem to combine characters of beth the Peracaridan 

 and Eucaridan divisions of the Malacostraca, and must be excluded 

 from all the existing orders. It is by no means clear, however, 



