Figure 2. Dorsal view of a young Frog's cranium-- the membrane bones removed. Diagrammatic. Figures 3 and 4. Dorsal and ventral views, respectively, of the Frog's skull-- the lower jaw removed. Figure 5. Side view of the Frog's skull. Figure 6. Median section of the brain case. Figure 7. The hyoid apparatus. Figure 8. I., II., III., progressive stages of the Tadpole's skull from the side. After W. K. Parker. Figure 9. F., side and hind views of the Frog's skull. D., the same of the Dog. Roughly diagrammatic. N.B.-- In all cartilage is dotted, cartilage bone cross-barred, and membrane bone, white. In Figure 4, pt., should be cross-barred; and in 5, th.h. plain. a.c., anterior cornu of hyoid [(= CH.)] -not lettered, in {Figure} 5-. a.o., antorbital cartilage. ar., angulo-splenial -(On Frog Section 34, for Articulare read -Angulo-Splenial_)-. -b., parachordal part of brain box-. b.c., brain case. b.h., body of hyoid. b.r., branchial arches. CH = a.c. c.t., cornua trabeculi. d., dentary. e., eye. E.N., external nares. e.o., exoccipital bone. f., fenestra (membranous part of cranial wall). -f.p., fronto-parietal.- h.m., hyomandibular cleft = Eustachian tube and ear drum. mb., mandible. [M.C., Meckel's Cartilage.] m.mk., mento-Meckelian bone. m.p., mouth passage. mx., maxilla. n.c., notochord. n.o., nasal organ. n.p., nasal passage. ot., or o.c., otic (auditory) capsule. pal., palatine bone. PAL., hard palate of Mammal. p.c., parachordal. p.f., [parieto-frontal] -see f.p.- p.m., premaxilla. P.N., internal nares. p.o., prootic bone. p.p., palato-pterygoid cartilage. psph., parasphenoid bone. pt., pterygoid bone. q., quadrate cartilage. q.j., quadrato-jugal. s.e., sphenethmoid bone. sq., squamosal. t., trabecular part of brain box. t.c., trabecula. th.h., thyrohyal. {Illustration: Diagram Sheet 14.} Sheet 15 Figure 1. Dissection of -Male- [Female] Dog-Fish to show alimentary canal, the pericardium also being opened and the cloaca slit up. [Above is also seen the dorsal view of the head.] Figure 2. The pelvic girdle and fin skeleton [of a male]. {No Figure 3, in First Edition.} Figure 4. The spiral valve in the colon. {Figure 3, in Second Edition.} a.p., abdominal pore. aur., -auricle- [atrium] of heart. b.d., bile duct. b.pt., basi-pterygium. -cl., clasper.- cl.c., -its- [the] supporting cartilage [of the clasper]. co., colon. d'dnm., duodenum. e., the eye. g.bl., gall bladder. g.s., gill slits. L.Lv., left lobe of liver. M.Lv., middle lobe of liver. olf., olfactory opening. [pan., pancreas.] pcd., pericardial wall. pel.g., the pelvic girdle. p.p., arrow through pericardio-peritoneal canal. r.g., rectal gland. [R.Liv., right lobe.] sp., spiracle. spl., spleen. st., the stomach. s.v., sinus venosus. u.g.p., uro-genital pore. v., ventricle. {Illustration: Diagram Sheet 15.} Sheet 16. Figure 1. Circulation of the Dog-Fish.