PHYLUM CHORDATA 



417 



well-developed digits, and on the tibial side of the first is a 

 spur-like structure or calcar (C), formed of three bones, a 

 metatarsal and two phalanges : such a rudimentary digit is 

 called & pre- hallux. 



The mouth leads into a wide buccal cavity having in its 

 roof the posterior nares (Fig. 251,/. ?ia), a pair of projec- 

 tions due to the downward bulging of the large eyes, and the 



°y\ crbh I \=blm\ n.i 



gut 



Fig 251. — Rana temporaria. Disseciion from the leftside; the viscera somewhat 

 displaced, an, anus; b. d, bile duct; b. hy, body of hyoid; 61, urinary bladder; 

 bV ', its opening into cloaca; c art, conus arteriosus; cblm, cerebellum; el, 

 cloaca; en. ?, centrum of third vertebra; cp, ad, corpus adiposum ; crb h, cere- 

 bral hemisphere; d. ly. s, dorsal lymph sinus; rtT«, duodenum; ep. cor, epicora- 

 coid; ens. t, Eustachian tube; FR. PA, fronto-parietal; gl, glottis; gul, gullet; 

 IL, ilium; is, ischium; kd, kidney; 1. an, left auricle; Ling, left lung; lr, 

 liver; m. mck, menco-meckelian; «. a. j, neural arch of first vertebra; olf.l, 

 olfactory lnbe; opt I, optic lobe; o. st, omo- and epi-sterntim; ftcd, peri- 

 cardium; P/lfA', premaxilla; pn, pancreas; P na, posterior naris; pit, pubis; 

 ret, rectum; r. Ing, right lung; s.int, small intestine; sp.cd, spinal cord; 

 SPH. eth, sphenethmoid; spl, spleen; st, stomach; s.v, sinus venosus; tng, 

 tongue; ts, testis; ur, ureter; ur', its aperture into the cloaca; ust, urostyle; 

 z>, ventricle; v ly. s, ventral lymph sinus; vo. t, vomerine teeth; vs. sem, 

 vesicula seminalis. 



Eustachian tubes (eus. t, vide infra). On its floor is the 

 large tongue (tng), attached in front and free behind, where 

 it ends in a double point ; by means of its muscles it can be 



2 E 



