590 H. H. SWINNERTON. 



semicircular canal runs. b. Brain, b. f. Fore-brain, b. h. Hind brain, b.m. 

 Mid-brain. br. Branchial arch, br, b. 1 — 4. Basibrancliials 1 — 4. br. c. 

 I — 5. Ceratobranchials 1—5. br. e. 1 — 4. Epibranchials 1 — 4. br. h. 1 — 3. 

 Hypobranchials 1 — 3. br.j). 2—4. Pharyngo-branchials 2 — 4. br. r. Branchi- 

 cstegal ray. ca. Foramen for internal carotid artery. cli.^wAch'. Notochord. 

 d. Denlaiy. e. Ethmoid region, e. m. Mescthmoid. e. m. c. Mesethmoid 

 cartilage. e. p. b. Parethmoid bone. e. p. c. Parethmoid coriiu. e. pr. 

 Pre-ethnioid cornu. e. pr. b. Pre-etlimoid bone. ep. Epiphysis, ep. c. 

 Epipjiysial cartilage, ep.f. Epiphysial foramen, ep. s. Connection between 

 epiphysis and supra-occipit.al region, ei/. Eye. si/, c. Eye-muscle canal, fe'. 

 Fenestrae in the floor of the auditory capsule, /e" . Feuestrse in the side wall 

 of the auditory capsule, fr. Frontal. //. Process from frontal, g. Gape. 

 ^^. Hyoid arch. h_y. b. Basiliyal. //_y. c. Ceratohyal. hy.c'. Process of the 

 ceratohyal. hy. e. Epihyal. hy.h.\, 2. Hypohyal 1, 2. hy. i. Stylohyal. 

 Iiym. Hyomandibular. hym'. Opercular process of the hyomandibular. hym". 

 Articular processes of the hyomandibular, hym'". Articular facets for the 

 hyomandibular. inf. Infundibulum, /. Labial cartilage. /. Labial fold. 

 m. e. External rectus muscle, mk. Meckel's cartilage, m.i:. Maxilla, 7ia. 

 Nasal, na . Process of nasal bone, o, e. Epiotic. o. p. Pterotic. o. pr. 

 Pro-otic. o.pr'. Pro-otic process, o. ;»•". Anterior end of the parachordal. 

 0. sp. Sphenotic. oc. a. Occipital arch, oc. a'. Small process on the occipital 

 arch. o<;. A. Basioccipital. ot;. c. Occipital choudrification. oc, (?. Exoccipital, 

 oc. n' . First occipital nerve, oc. n" . Second occipital nerve, oc. s. Supra- 

 occipital, op. Operculum, op. i. Literoperculum. op. pj\ Pre-operculum. 

 o/j. 5. Suboperculum. /;. c/^. Parachordal. /?. c/*'. Interparacliordal fossa. /)./, 

 Posterior cranial foiitanelle. p. t. Post -temporal, pa. Palatine, pa'. Pre- 

 palaiine articular facet, pu" . Post-palatine articular facet, pa. m. Maxillary 

 process of the palatine, par. Parietal, pff. ec. Ectopterygoid. pg. en. Ento- 

 pterygoid. pg. m. Meta|)terygoid. pmx, Premaxilla. pmx' . Cartilage on the 

 ascending process of the premaxilla. ps. Parasphenoid. /«'. Median process 

 of llie paraspher.oid. pa" . Lateral process of the parasphenoid. pt. Pituitary 

 body. pl-f. Pituitary fossa, qu. Quadrate, qu . Process of quadrate, qti. m. 

 Metapterygoid process of the quadrate, qu. pa. Palatine process of the 

 quadrate, qu. pel. Pedicular process of the quadrate, r. Rostrum, sb. b. 

 Supra-orbital band, sb. p. Post-orbital process, so. 1—3. Suborbitals 1 — 3, 

 sy)iu Symplectic. (g. Tegmen cranii, Ir. Trabeculae. I/. Point of union of 

 the trabeculae with the parachordals, vo. Vomer, .r. Infra-symplectic 

 cartilage. 1 — X. Nerve foramina. * Boundary between the head and body, 

 ** Curve of the egg-shell, f Articulation between palatine and pterygoids. 



Fig. 1. Stage I. — Dorsal view of the chondro-cranium of a larva, 3'6 mm. 

 long. X 70. 



Fig. 2. Stage II. — The same of a larva, 57 mm. long, x 60, 



