CHITONIDZE. . 247 
of the class, from which they are inseparable, but there is 
scarcely a group of Mollusca to which they are not allied. 
The posterior termination of the rectum is not without ex- 
ample; it is essentially the same in Fisswrelia, and more or 
less so in many of the Bulliide and Pleurobranchide. M. Des- 
hayes observes, that the want of eyes and tentacula has been 
adduced as denoting affinity with the Annelida; but, as we 
have already observed, why not compare these deficiencies 
with the Conchifera, their immediate predecessors? And as 
regards the Gasteropoda, the absence of eyes and tentacula is 
not unusual: for instance, Bulla cylindracea has not a trace 
of these organs; the Velutina otis of authors, Mr. Gray’s 
Otina, has no tentacula; some of the Bullide are without 
eyes, and others without tentacula; there are examples of the 
Natice without eyes, and in the Dentalia both eyes and tenta- 
cula are absent. Dentaliwm,in my method, is placed in the 
van of the Gasteropoda, and Chiton follows ; both are closely 
allied, and, we think, appropriately succeed the Conchifera. 
I do not say that, with the latter, the characters of alliance 
are very decided; still, on examination there will be found 
analogies: for instance, in Chiton and Dentalium the branchiz 
are placed symmetrically, though varying in particular posi- 
tion. In Chiton, though not in Dentalium, the anus has the 
same posterior site as in the Conchifera and in some of the 
patelloid forms. The strict sexual order of hermaphroditism 
appears to obtain in both, and throughout the Patelloida to 
the Pleurobranchide and Bullide, in which a more influential 
plan of reproduction commences. These notes, in conjunction 
with the special typical ones, only call for a very brief sum- 
mary, and we think a calm review of all the circumstances 
that are adduced will go far to convince zoologists that there 
is not a locus standi for any organ in Chiton contrary to 
mollusean essential characters ;—all are confirmatory of the 
Chitonide belonging to that class, and the only return we can 
make per contra is—anil. 
It has been suggested by Professor Forbes in the ‘ British 
Mollusca,’ vol. 11. p. 390, that an examination of the foetal 
metamorphoses of the Chitons would throw light on their 
