Recent Literature. 153 
We have fault to find with the lettering and other signs affixed to 
the paragraphs of the analytical keys of the various divisions. Were 
it not for the indenting and correct ranging of these paragraphs, 
their relations to each other could be only discovered by a consider- 
able study of the signs affixed, and then many students, we suspect, 
would be hopelessly confused. The same system or unsystem has 
been adopted by Mr. Dobson in his catalogue of Chiroptera. It is 
to be sincerely hoped that in future the taxonomic keys may be ar- 
ranged on the usual plan, such as for instance is employed by Mr. 
Boulenger in his catalogues of the Batrachia and Reptilia. 
The twenty-eight plates are a welcome aid to the study, but the 
dental cusps are often poorly represented. 
The Classification of the Crinoidea appears now to have 
reached sound and rational basis as is clearly set forth in a 
recent important contribution* to Crinoid morphology by Messrs. 
Charles Wachmuth and Frank Springer. Although the sub- 
ject is approached chiefly from a palaeontological standpoint, mor- 
phological deductions derived from the latest researches among living 
crmoids have been duly considered. The systematic arrangement 
of the Crinoidea as indicated is of not less supreme interest to the 
palaeontologist than to the biologist ; and the classification as now 
proposed appears to be practically in agreement with the views of Dr. 
P. Herbert Carpenter, the distinguished English authority on recent 
crmoids. The necessity of a radical change in the existing classifi- 
cation centers around the discovery of the ventral structure in 
Taxocrinus. It is now clearly demonstrated that in this genus, and 
doubtless in the Ichthyocrinidae generally, the mouth is open, and 
surrounded by five conspicuous oral plates, as in the recent genera 
Rhtzocrinus, Bathycrinus, Hyocrinus and Holopus j thus differing in 
structure very materially from other palaeozoic crinoids, which have 
the mouth closed. In the latter group, as is now conclusively shown, 
the orals are the hitherto denominated "central" and four "proxim- 
ate dilates. The plan upon which modern crinoids are constructed 
IS therefore one of high antiquity, dating back geologically to the 
1-ower Silurian. 
The Crinoidea are thus divisible into 
1. Camarata. 
2. Inadunata, comprising the branches Larviformia and Fis- 
3- Articulata, including Ichthyocrinidae and possibly Uintacrinus 
and Thaumatocrinus. 
. 4. Canaliculata, including most of the mesozoic and recent 
crinoids.— C. R. K. 
» piscovery of the ventral structure of Taxocrinus and Haplocrinus, and conse- 
quent modifications in the classification of the Crinoidea.— By Charles Wachsmuth 
Frank Snr..„., t._...... '': Academy Natural Sciences. Philadel- 
