200 
PALEONTOLOGY OF NEW YORK. 
anterior extremity, so that in extremely small individuals the carapace is 
very short and cordate in outline. These variations in outline have been 
regarded by the Committee of the British Association on the Fossil Phyllo- 
poda (Second and Third Repts., loc. cit.) as of specific value, but abundant 
material leaves no doubt that the difterence is developmental and not 
specific. Specimens are not infrequently found folded symmetrically along 
the dorsum, although there is no evidence of any dorsal suture or anchylosis 
along that line. The substance of the test is chitinous and very thin. 
Dimensions. The variation in size exhibited by specimens of this, species 
is considerable. The average normal adult represented by the type specimen 
having a length of 28 mm., and a width of 16 mm.; the smallest individual 
observed is 2 mm. long and 3 mm. wide. A very large fragment indicates a 
shield upwards of 80 mm. in length. 
Distribution. Widely distributed throughout the lower horizons of the Portage 
group as originally defined (“ Naples beds,” Clarke), in the towns of Bristol, 
Richmond and Naples, Ontario county; Sparta and Son Yea, Livingston 
county; and in the upper sandstones of the group at Naples and Canadice, 
Ontario county ; Portageville, Wyoming county. 
DIPTEROCARIS, Clarke. 1882. 
DiPTEROCARIS PENNiE-D^DALI. 
PLATE XXXV, FIG. 24. 
Dl-pterocaris ‘pemKB-Bmdali, Clarke. Amer. -Jour. Science, Third Series, vol. xxv, p. 122, tig'. 1. 1883. 
Di^terocarls pennOd-DmdaU, Jones and Woodward. Geol. Mag., Dec. iii, vol. i, No. 8, p. 349. 1884. 
Dipterocaris 'pmmCB-BcBdali, Etheridge, Woodward and Jones. Second Kept. Committee on Fossil Phyl- 
lopoda of the Palteozoic Rocks, p. 11. 1884. 
BijJterocaris penncB-DcBdaU, Etheridge, Woodward and Jones. Third Rejit. Committee on Fossil Phyl- 
lopoda of the PaliEozoic Rocks, p. 3. 1885. 
The original of this species consists of but one-half or one ala of the 
Carapace, which is very elongate, with the lateral margin straight, the anterior 
angle nearly ninety degrees and the posterior angle acute. The area of union 
(“isthmus,” Jones) is anterior, the cephalic cleft narrow, and the margin of the 
