206 REPTILIA : TESTUDINATA. — X.W. 



aa. Nostrils terminal, crescent-shaped; a prominent lonpitiidinal ridge project- 

 ing from each side of septum ; head broad ; edge of iip[H-r jaw entire. 



Am'Iuonectes, 306. 



305 AMYDA A^'assiz. (Lat., turtle.) 



599. A. mutica (Lc Sueur). Lkatukr-Tukti.k. A dejircs- 

 sion alouj^ niediau liiK" of earupace ; no spines nor IuIktcIcs along 

 anterior marjfin nor on l)aek. Olive, youni^ spotted ; feet not mot- 

 tled lielow. L. 12. Canada to Ohio R., and N. W. (Lat., un- 

 armed . ) 2 />.i_r-»vM -*- 



3C6. AGriD Ot^g CgBS W'agler. (danis, shield ; f^KTrji, 

 swimmer.) 

 a. Ixuvcr narts nf lnnly and feet sj)otted with dark. 



600. A. TB pintfcr (Lc Sueur). Com.mon Soft-siikij.kd Tcr- 

 Ti.E. Caraj)aee olive brown with dark spots ; head and neck olive 

 <;reen with light and dark stripes ; legs and feet mottled every- 

 where with dark; ^ with the tubereles on the front of the earapaee 

 snuiUer than in the 9» *l'^' hody also longer and the tail e.xtemling 

 considerably Ix^yond the margin of the earapaee. Canada to Ky. 

 and Minn., abundant. (Lat., spine-ln-aring.) 



601. A. nuchalis Agassiz. A marked depression on either side 

 of the blunt median keel, which is dilated and triangular anteriorly; 

 spines and tubercles prominent in (J. Cuml)erland and L'j)per 

 Tenn. Rivers. 



aa. Lower parts of body and feet white. 



602. A. agassizi Haur. Tubercles on shell largest in ^\ back 

 blotched in adult ; young with black spots and ocelli and with 2 or 

 3 concentric bluck marginal lines. S." Ind. to Ga. and La. 



Family CXX. CHELYDRID^. (Tiik .Sxappixg 

 'IrKri-Ks.) 



Shell high in front, low behind ; body heaviest forward : heail and 

 neck very large, the snout narrowed forward; jaws strongly luMiked, 

 and very powerful ; tail long, strong, with a crest of horny, com- 

 pressed tubercles ; plastron small, cross-shaped, with 9 jtlates be- 

 sides the very narrow bridge. Claws 5-4, strong, the web small. 



Large turtles of great strength and voracity, chiefly acpiatic ; 2 

 of the 3 species are American, the third {Plalysternum) is from 

 China. 



a. Eyes close together, partly superior; head covered with soft skin ; tail with 

 two rows of moderate scales beneath ; ridges of cnrajmce becoming obsolete 



with age; jaws niodemtcly hooked C'iiKt.Yi>HA, 307. 



aa. Eyes distant, lateral; head vi-ry large, covered with smooth, synunefrical 

 plati-s; tail with many small imbricate scales beneath; carapace with 3 

 large [H:rsistent kcclii; jaws very btruugly hooked. 



Macrociiklts, 308. 



