CONTRIBUTIONS TO THE NATURAL HISTORY OF QUITO. 695 
habiting the subterranean waters of the Andes and thrown out in 
the eruptions of Imbabura and Caraguairazo. There are several 
species of the same family in the Esmeraldas, as P. cinerascens, 
P. elongatus and P. modestus. 
MOLLUSCS. 
There is little variety of molluscan life on the Andes. The 
land-snails predominate, belonging to the Helicide and Cyclosto- 
mide. The presence of the old world genus Clausilia, wanting 
in North America, becomes a significant fact, as Woodward ob- 
serves, when taken in connection with the affinities of the higher 
animals of South America and Africa. ‘These imply a land-way 
across the Atlantic at some very remote period.” 
The known fresh-water shells in the valley are few in number, 
and the exact localities of these cannot be positively given. Cas- 
talia Crosseana Hid., and C. Pazi Hid., are credited to Imbabura ; 
Hemisinus Pazi Tryon, H. simplex Tryon, H. Osculati Villa, 
Ampullaria modesta V. d. Busch and A. solida V. d. Busch to 
Quito; and A. Quitensis V. d. Busch to Ecuador. But Mr. Tryon 
informs me that the locality of Hemisinus is not certain ; and as I 
collected none myself, I am doubtful of all the others except 
Castalia. Hemisinus Binneyi Tryon, may be added to this pro- 
visional list. 
The type of the genus Arges (A. sabalo C. and V.), from the position of the eyes and 
ventral fins, may possib hy remain as the type of a genus under that name, distinct from 
pera genus Stygogenes, which I consider as covering my specimen as ide 
n chm ldtii i ss brachye cephalus, which I consider the same as Ameer 
er 
Pim cyclo; 
ra puig isi k as -Günther intludes it (doubtfully) as a distinct species s his genus 
Stygogenes, and as Swainson also named it Cyclopium Humboldtii, we have a singular 
confusion of ents which, following the strict law of priority of names erg should 
be rendered thus 
niger ge (Sw.) cyrcLopum (Humb.) 
Sy 
; i us cyclopum Humboldt, 
Aa petna Humboldtii Swainson, 1838-9. 
3. Arge Cuv. and Val., 1840. 
Of ihono essen nanea a se oan er 1,2; ii d 6 were unquestionably pro- 
posed p from sed wholly because Humboldt 
did not mention the spine gee B e 2d dorsal. No. 4 was considered as distinct, and 
placed in a separate genus on account of the ong not being present. The specimen 
now under examination re a feo and with it all the characters given of the species, 
hence I unite them all as one under a aoa non-euphonie designation of Cyclo- 
um pum, adding one more name to the list, which will be adopted, or classed as 
a synonym, according to foodie eee ut which, nevertheless, is the name that 
should be used to designate the species if the strict law of priority is followed. 
