40 
PROCEEDINGS OF THE ACADEMY OF 
the day before the reception of the proof of the foregoing paper, and conse- 
quently too late to compare my views with those of the distinguished author. 
I am happy to find that the validity of the groups of Viviparidae, which have 
been above defined, is confirmed by the researches of Dr. Troschel, who has 
examined the dentition of several species of true Viviparus , besides that of the 
Paludina subcarinata of Say, for which he has proposed the name Lioplax. The 
latter name is now substituted for Haldemania of Tryon, and is modified to form 
the name of a group containing that genus and Melantho. 
Additional Remarks on the North America JEGIOTHI. 
BY ELLIOTT COUES, A. M., M. D. 
Since the publication in the Proceedings of the Academy for November, 
1861, of my Monograph of the genus, the Smithsonian has been constantly in 
the receipt of additional specimens from all parts of North America. These 
were mostly the A. linarius ; but collections from the North have usually 
contained a number of well-characterized examples of A. exilipes. Nothing, 
however, of special importance has been elucidated, until the reception of a 
series collected in winter in the vicinity of Quebec. These specimens, as they 
throw much light on the variations of the typical species of the genus, 
A. linarius , will merit a brief notice. If the deductions I have drawn from 
these specimens are warrantable, we have in North America the forms long 
recognized in Europe as A. Holbolli and A rufescens ; and these are both rather 
races than distinct species. 
Selecting from the series two or three skins which differ most markedly from 
the usual style of linarius , and comparing them with a typical specimen of the 
latter from Philadelphia, I find the following differences : 
The bird is very decidedly larger. The difference in total length is nearly 
one inch, as near as I can judge from the dried skins. The wings and tail are 
each about a fourth of an inch longer. The tarsus and middle toe with its 
claw are together about two-tenths of an inch longer.* The bill and feet are 
decidedly larger and stouter, though perhaps not disproportionately so. The 
former is somewhat elongated ; its lateral outlines straight instead of a little 
concave ; its culmen slightly curved. The bill is of a bright chrome-yellow, 
except just along the culmen and at the extreme tip. The gular spot seems 
rather large. In other respects, the two birds- are quite identical, for, with 
these differences in size, there is an exactly proportionate increase in the bill, 
feet, wings and tail ; and the colors of the two do not differ appreciably, ex- 
cept in the bill, and perhaps the larger gular spot. The specimens give the 
idea, in fact, of overgrown individuals of the common linarius. 
But now, on examining in detail the rest of the series, I find that, from 
the one extreme, the characters of which have just been given, there is a com- 
plete and gradual transition, — a diminution in size, down to specimens which 
cannot possibly be distinguished from typical linarius. There is no break in the 
series ; no dividing point where we can stop calling the specimens “ linarius ” 
to give them another name ; in spite of the discrepancy which is so evident 
between the two extremes. 
The point of interest which attaches to these specimens, is the bearing they 
may have on the mooted question of the claims of AEgiothus Holbolli to full 
specific rank. As was the case at the time of the preparation of my Mono- 
graph, I have never examined a specimen which professed, upon good Euro- 
pean authority, to be that species. Careful examination, however, of the 
*Tne tarsus, middle toe and claw together, of the specimens under consideration, measure 
absolutely 1-20 inches ; the same parts in Unarms are about one inch : ill exilipes -80 of an 
inch. 
[Feb. 
