PHYLUM CHORDATA 



4i7 



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 a pre-ha/Iux. 



The mouth leads into a wide buccal cavity having in its 

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

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



gut 



Fig. 251. — Rana temporaria Dissection from the left >ide: the viscera somewhat 

 displaced, an, anus; b.d, bile duct; b. ky, body of hyoid ; bl, urinary bladder; 

 bl' ' , its opening into cloaca ; c . art, con us arteriosus; cbhn , cerebellum ; c', 

 cloaca; en. 3, centrum of third vertebra; cf>. ad, corpus adiposum; crb. h, cere- 

 bral hemisphere; (/. ly, s, dorsal lymph sinus ; dn, duodenum ; ep. cor, epicora- 

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

 IL, ilium; is, ischium; kd, kidney; I. an, left auricle; I. Ing, left lung; Ir, 

 liver; \i. MCK, mento-meckelian : ;/. a. 1, neural arch of first vertebra; elf. I, 

 olfactory lobe; opt. I, optic lobe; o. ST, omo- and epi-sternum ; ped, peri- 

 cardium; PMX, premaxilla; p?i, pancreas: / na, posterior naris; pa, 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: tug, 

 tongue; ts, testis; »r, ureter; ur' , its aperture into the cloaca; UST, urostyle; 

 v, 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) y attached in front and free behind, where 

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



