WOODWARD — SOME ACCOUNT OF BAERETTIA. 
375 
in which the plate is wanting, and the cardinal apparatus lies close to 
the side of the shell instead of being at right angles to it.* We 
have already described and figured these peculiarities on former oc- 
casions, and it will be sufficient now to propose the name Dorhignia 
for R.U oculatus and other hippurites (figs. 6, 7), which have no 
ligamental inflection, and a second subgeneric title, Barrettia, for 
the Jamaica fossil, which presents the further peculiarity of an indefi- 
nite number of pallial duplicatures extending all round the margin of 
the lower valve. 
It still remains to speak of the shelly process from the upper 
valve {a!), seen in both our sections, descending into a pit between 
the posterior tooth {t') and the principal duplicature (w). In the 
paper previously referred to we liave described this process as the 
support of the posterior shell-muscle, having found characteristic 
indications of the muscular scar within the cavity which receives it. 
Since then, Professor Bayle, of the Ecole des Mines at Paris, has pub- 
lished a description, with excellent figures, of some very complete 
examples of Hippurites radiosiis. These specimens do not show any 
peculiarity unknown before, but they are far more perfect than the 
best we had ever seen, and exhibit in complete relief the extra- 
ordinary cardinal apparatus of the upper valve, of which our previous 
knowledge was chiefly obtained from sections. Owing to the condition 
of his specimens, M. Bayle has had the good fortune to procure, in a few 
weeks, better illustrations than we could obtain with much labour, 
continued at intervals for several years. Nevertheless, the very state 
of our materials has compelled a closer and longer examination, which 
we trust has not been thrown away ! M. Bayle has quoted our views 
very fairly, and we hope he will yet see reason to adopt them. His 
memoir was accompanied by a critical notice from M. Deshayes con- 
taining the following passages : — 
" Le travail de M. AVoodward est le plus complet qui ait ete publie 
sur I'ensemble des Eudistes. Cependant il reste bien des parties qui 
auraient demande une discussion plus approfondie, des caracteres qui, 
au point de vue zoologique, auraient pu etre plus largement exposes 
et discutes." 
" Avec le travail de M. Woodward, on pouvait encore concevoir 
des doutes sur quelques parties, et notarament sur le nombre et la 
position des muscles. Ce naturaliste suppose I'existence d'un 
muscle adducteur des valves de chaque cote de la charniere, exacte- 
ment comme dans les Spherulites ; ce second muscle se serait at- 
tache dans la profondeur de Tune des cavites cardinales de la valve 
inferieure et au sommet de I'une des apophyses de la valve supe.^ieure ; 
mais les pieces preparees par M. Bayle ne laissent plus de doute a ce 
sujet ; les deux impressions musculaires sent portees d'un meme 
cote, par suite d'un renversement de I'animal, comparable a ce qui 
existe chez les Hippopes et les Tridacnes, aiusi que M. Bayle lui-meme 
I'a parfaitement compris ; tout I'appareil musculaire, se trouvant 
* 'Manual of the Mollusca,' pt, ii. p. 279 (1854), and Quarterly Journal of the Gool. 
Soc, vol. xi. p. 40, 1855. (Read May 24, 1854.) 
