282 Rey. 8S. Haughton on the Muscular 
Microphysa, Westw., was rejected because the characters laid 
down were drawn only from the female of one species, differing 
greatly from the male, while those of Zygonotus, Fieb., included 
both male and female. : 
The remarks about Hydrometra and Gerris appear to be well 
founded, the majority of authors having overlooked the fact of 
the priority of Latreille’s generic name Hydrometra for the. 
species stagnorum. Even Burmeister has done so; for in a 
note under Limnobates, a genus he established for this species, 
he says:—‘ Die Aenderung des Gattungsnamens wurde 
dadurch néthig, dass ich den Namen Gerris fiir die von Fabri- 
cius in diese Gattung gestellten Arten beibehalten zu miissen 
glaubte, da er das Recht der Anziennitat fiir sich hat.” Hy- 
drometra, Lat., should be the generic name for stagnorum, and 
Gerris, Fab., be restored to the species of Hydrometra of 
authors. 
In these remarks we have been careful not to travel beyond 
the record. The argument touches only a few points on the 
surface of a great subject (the real signification of genera), 
about which no two authors are agreed. The so-called “ ana- 
lytic method,” for instance, so much in favour, tends to the 
infinite multiplication of genera; so that we are in danger of 
realizing the taunt of Curtis “that every species would con- 
stitute a genus,” or of going a step further, and, by adopting 
Amyot’s ‘“syst#me mononymique,” which gives to every 
creature a new and single name, abolish genera altogether. 
XXXVII.—On the Muscular Anatomy of the Alligator. By 
the Rev. SamueL Haueuton, M.D., F.R.S., Fellow of 
Trinity College, Dublin. 
[Plate X.] 
In the sixteenth volume of the ‘Annals of Natural History’ 
(3rd series, p. 326) I published an account of the muscular 
anatomy of the leg of the Egyptian Crocodile (1865). Since 
that time I have had an opportunity of studying the anatomy 
of the Alligator of the Mississippi (June 1866). The specimen 
dissected by me was a female, upwards of 63 feet in length. 
Its examination confirms, in most respects, the conclusions at 
which I arrived from the dissection of the smaller specimen of 
Crocodile previously described; and I believe the results of 
my dissection are worthy of being recorded. 
Mr. Hair, of Edinburgh, has kindly forwarded me a copy of 
a paper on the Alligator, read by him as a thesis in the Uni- 
