MURIDH-—ARVICOLINAX—ARVICOLA PINETORUM. 219 
Back under molar with three spherical-triangular dentine islands in 
single series reaching across the tooth. Middle under with posterior spher- 
ical triangle; then interior closed triangle; then exterior closed triangle ; 
then two angles generally confluent, but sometimes separated by enamel 
wall into two (interior first, exterior afterward) lateral closed triangles. 
Front lower with posterior spherical triangle; then interior closed triangle ; 
then exterior closed triangle; then another internal closed triangle; then 
the two next lateral angles (one on each side) not separated and closed by 
a median enamel zigzag, but their dentine areas confluent, and moreover 
running into the dentine island of the anterior trefoil—this trefvil of 
variable shape. Thus there are five internal and four external angles in 
all (counting the lobes of the anterior trefoil). Front upper molar with an 
anterior spherical triangle, two interior and two exterior lateral closed 
triangles, the last exterior one being postero-lateral. Second upper molar the 
same, but with one less interior triangle—an exterior one comes first, then 
the interior one, then the postero-external one: the latter does not develop 
the postero-internal snag usually seen in Myonomes. Back upper with an 
anterior spherical triangle; then another like it reaching quite across the tooth, 
but with its posterior median angle long and acute, and running into the 
concavity of the posterior U, V, or Y that finishes the tooth. However this 
last may vary in details, it never approaches the oblique crescent charae- 
teristic of Myonomes. 
We only know one North American species of this section; a second, 
however, occurs in Mexico. 
ARVICOLA (PITYMYS) PINETORUM (LeConte). 
Pine Mouse. 
Arvicola pennsylvanica, HARLAN, Fu. Amer. 1825, 144 (in part; the description,” but not the synonymy. 
Not of authors). 
Psammomys pinetorum, LEContr, Ann. Lye. Nat. Hist. N. Y. iii, 1829, 132, pl. ii. (Name inept.) 
Pitymys pinetorum, McMurrrie, Am. ed, Cuy. R. A. i, 1831, 434. 
Pinemys pinetorum, Lesson, Nouy. Tab. R. A, 1842, 12. 
Arvicola pinetorum, AuD. & Bacu., Q. N. A. ii, 1851, 216, pl. Ixxx (excl. syn. “oneida DeK.”).—LEConTE, 
Proc. Acad. Nat. Sci. Phila. vi, 1853, 409. 
Arvicola (Pitymys) pinetorum, Barrp, M. N. A. 1857, 544.—ALLEN, Bull. Mus. Comp. Zool. i, No. 8, 234 
(Massachusetts ; rare; ‘‘ probably its northern limit”).—ALLEN, op. cit., ii, No. 3, 184 (Flor- 
ida).—CouEs, Proc. Acad. Nat. Sci. Phila. 1874, 191. 
Arvicola scalopsoides, AUD. & Bacu., Journ. Acad. Nat. Sci. Phila. vill, 1842, 299 (Long Island).—WaAGNER, 
Wiegmann’s Archiv, 1843, 53.—LeContr, Proc. Acad. Nat. Sci. Phila. vi, 1853, 409. 
Arvicola apella, LECONTE, Proc. Acad. Nat. Sci. Phila. vi, 1853, 405 (Pennsylvania).—Avupb. & Bacn., Q.N. 
A. ili, 1854, 289. (Same as LeConte’s. ) 
; *< Above a brownish fawn; beneath grayish-white; * * length 4 inches; tail % of an inch ; 
* * the teats of the female are situated very pear the organs of generation; she carries her young 
between the hind legs.” —HAk Lan, l. ¢. 
