448 
Order CresTo1pEa. 
5. TETRABOTHRIUM GERRARDII. 
The genus Tetrabothrium was indicated by Rudolphi in his 
‘Synopsis Entozoorum,’ for containing those species of Bothrioce- 
phalus which possess four bothria. It was afterwards fully adopted 
and characterized as a distinct genus by Diesing ; and nine species are 
described by him. These were discovered all inhabiting the intestines 
of certain Mammalia, Birds, and marine Fishes ; but none of them 
have been, till now, recorded as living in Reptiles. 
The species now to be described, however, was found, by Mr. 
Edward Gerrard of the British Museum (to whom I am indebted for 
an opportunity of describing several new species of Entozoa), in the 
intestines of a Boa constrictor from South America. 
The head is large, tetragonal; the four bothria disposed cross- 
wise, joined by the margins; each of them large, round, and having 
on one side a strong ridge. Body depressed, narrow, articulated. 
No distinct neck. Anterior extremity of body very narrow, and the 
articulations there are extremely small, becoming larger as they de- 
scend, the inferior being quadrangular and rather large. The margins 
of the articulations somewhat annulated, but having no appearance of 
genital apertures. The head is about three-fourths of a line broad ; 
but I could not discover any mouth. Apparently only fragments of 
_ these worms were obtained ; but some of these detached pieces were 
about 18 inches in length. 
Hab. Intestines of Boa constrictor. 
5. A CoMMENTARY ON M. Desuayes’s REviIsION or THE GENUS 
TEREBRA. By Loveuu Reeve, F.L.S., erc. 
In the ‘ Proceedings ’ of the Society for last year, pp. 270-321, is 
a paper by M. Deshayes, entitled “A general Revision of the genus 
Terebra.” Though most carefully elaborated, M. Deshayes was 
induced to undertake the revision of this genus of pectinibranchiate 
mollusks under circumstances hardly favourable to the correct dis- 
crimination of the species. Specimens of apparently new forms 
of shells were transmitted to him in Paris from the Cumingian col- 
lection, and they were described in the ‘ Journal de Conchyliologie’ 
as new, without having been submitted to the test of a comparison 
with the types of previously described species, most of which were 
known only in this country. 
Many of M. Deshayes’s new species of Terebra have been described 
already; and many have been described by him as new, which a more 
extended series of specimens would have shown him to be merely 
varieties. 
Out of 221 species of Terebra cited by M. Deshayes in his “ Ge- 
neral Revision,” I have been so fortunate as to collect undoubted 
types of 214. M. Deshayes has himself generously sent me the 
types in his own very interesting collection. The remainder are 
