It. AMERICA. 3 



scribed as new. (Lea) Description of a new subgenus of Najades, Plagiodon % 

 and of a new species of Triquetra — p. 79. (Same) Description of new fresh- 

 water shells from California — p. 80. Pompholyx effusa, Melaniashastaensis, 

 nigrina; Physa triticea ; Planorbis traskii ; Lymnsea proxima; Ancylus patel- 

 loides ; n. spp. (Same) Descriptions of twenty-five new species of Unio — p. 92- 

 95. Paleontology. (Leidv) Extinct Mammalia, discovered by Dr. Hayden 

 in the Mauvaises Terres of Nebraska — p. 59, 88-92. (Same) Kemains of a 

 species of Seal, from the Post-Pliocene deposit of the Ottawa river, Canada ; with 

 a plate — p. 90. (Same) Notices of extinct Eeptilia and fishes discovered by Dr. 

 Hayden in the Mauvaises Terres of the Judith river, Nebraska territory — p. 72. 

 (Same) Description of two Ichthyodorulites — p. 11. (Lea) Tooth of a Sauroid 

 reptile, Cenlemodon sulcatus, from the shale of the new red sandstone of Pennsyl- 

 vania — p. 77. (Newbeiry) Description of several new genera and species of 

 Fossil Fishes, from the carboniferous strata of Ohio— p. 96-100. The names 

 of the new genera are, Mecolepis and Compsacanthus. < (Meek and Hayden) 

 Descriptions of new species of Gastropoda from the cretaceous formation of 

 Nebraska territory — p. 63-69. (Same) New species of Gastropoda and Cepha- 

 lopoda, from the same— p. 70 72. (Same) Twenty-eightnew species of Acephala 

 andone Gastropod, from thesame — p. 81-87. (Shumard and Yandell) Eleuthe- 

 rocrinus, new fossil genus of the family Blastoidea, from the Devonian strata, 

 near Louisville, Kentucky; with a plate — p. 73 75. 



The Ameeican Jouenal of Science and Aets. Conducted by Professors Sillim an 

 and Dana. Second Series. 8vo. New York. 

 Vol. XXII. ; with three Plates and a Map. July-November, 1856. 

 Zoology. (Valenciennes and Fremy) On the Composition of the Muscles in 

 the Animal series : from the Journal de Pharmacie, a.d. 1855 — p. 9-13. (Dana) 

 Keview of the Classification of Crustacea, with reference to certain principles of 

 classification — p. 14-30. We extract from Wiegmann's Archives a critical 

 opinion, by Gerstaecker, upon the systematic views which Dana has put forth in 

 this essay : — " The fashion of artificial systems, long since abandoned in Europe, 

 seems still to have many adherents in America ; and, accordingly, the Dichotomous 

 classification in particular, based on single characters, is applied to the Crustacea 

 throughout the present work. Dana proposes to divide the class into Podoph- 

 thalma, Edriophthalma, and Cirrhipedia : the second of these groups should 

 have embraced all the members of the class which have not the eyes petiolated ; 

 but the author has felt himself obliged to separate the Cirrhipedia from the rest 

 on account of the discrepancy of their Habitus in their final state of development. 

 He would have carried out the principles of the artificial classification more con- 

 sistently by retaining them among the Edriophthalma ; and this group, in his 

 acceptation, already comprises such heterogeneous elements that the addition of 

 the Cirrhipedia need not have seemed to present a greater difficulty. To us it is 

 plain that the conjunction of the Entomostraca with thelsopoda and Amphipoda 

 in a group equivalent to theDecapoda is inadmissible ; since the latter two, not- 

 withstanding their sessile eyes, might be combined in one great group with the 

 Decapoda, more naturally than with the Entomostraca. Further, the author in- 

 cludes the Rotifera among the Edriophthalma, without giving any reasons in de- 

 tail for this very questionable position of them ; and again the Pycnogonida are 

 combined with the Poecilopoda in the section Cormostomata of the Entomos- 

 traca, to which the Gnathostomata (Phyllopoda and Lophyropoda) and the 

 Merosomata (Limulidee) are opposed as co-ordinate. Many such anomalies, 

 which the exigencies of the Dichotomous arrangement may account for, but do 

 not justify, occur in this classification of Dana's. He has proposed manv genera 

 and species among which we might find ample scope for criticism. The moat 

 natural genera are often broken up into many, the characters of which are no 

 better than specific differences ; as tat example the genus Pagurus, of which 

 Milne-Edwards has rightly admitted only subordinate groups, according to the 

 position ot the large claw, as that the right or left hand ; the numerous transi- 



