Dec. 25, 1S73J 



NATURE 



U7 



THE COMMON FROG* 

 VII. 



''PHE skull of the fro^ presents numerous points of 

 -*- interest, but only four of these can be here referred 

 to, as other matters dcmnnd nur attention/^ 



Fig, 37. — Upper Surface of the 

 ceinture, or girdle-bone ; eo, 

 bone ; 7>tjc, maxillary bone : 

 fr onto -parietal bone ; pni, 

 quadrato-jugal; sg, squann 



Skull of a Frog (alter Parker), e, os cu 



exoccipital : /, frontal part of frontoparietal 



w, nasal ; o/>, opisthotic ; /, parietal part of 



prc-maxilla ; />o, pro-otic ; //, pterygoid ; f/, 



Fig. 38.-Under Surface of the Skull of a Frog (after Parker), c, girdle- 

 bone; eOt exoccipital : mx, maxilla ; par, parasphenoid ; /w, pre-maxiUa ; 

 /c, pro-otic ; //, pterygoid ; 7, quadrato-ju^al ; sits, suspensorium of 

 lower jaw, the lower end of which represents the quadrate bone ; v, 

 vomer ; i, oplic foramen ; 2, foramen ovale ; 3, condyloid foramen. 



Fiu. 39, Fig. 40. 



F1G.39— Diagram of the Larynx of Man, the thyroid cartilage being supposed 

 10 be transparent, and allowing the right arytenoid cartilage {Ar), vocal 

 ligament ( / '), and thyro-arytenoid muscle ( Th A), the upper part of the 

 cricoid cartilage {Cr), and the attachment of the epiglottis (£/l, to be 

 seen. C th, the right cricothyroid muscle ; Tr, the trachea ; f/y, the 

 body of the hyoid bone. The right lesser cornu appears as a very small 

 process, extending upwards and backwards from the body of the hyoid 

 behind the letters Hy, and in front o( the Epiglottis. The right great 

 cornu is shown extending backwards from the body of the Hyoid and 

 terminating beneath the letters Ep 



Fig. 40 — Extracranial portion of hyoidean apparatus of Dog, front views 

 sk, stylohyal ; ch, epihyal ; ch, ceratohyal (these three constitute the 

 ''anterior cornu") ; bh, basihyal, or "body" of hyoid ; M, thyrohyal, 

 or " posterior cornu." (From Flower's "Osteology.") 



* Continued from p. no 



The first of these four relates to its mode of articulation 

 with the vertebral column. As has been said the first 

 vertebra presents a pair of concavities to the skull. The 

 skull develops from its hinder (or occipital) region a cor- 



Fig. 41. 



~.. 41. — Skeleton of left serie 

 abave. 1, glosso-hyal ; 2, ^ 

 6, cerato-branchials ; 7, ■; 

 chials ; g. pharyngo-br.m 

 9", superior pha'ynge.i I !• 1 

 6'. 7', and g, second br.inri.i 

 arch : 5", 6"', and 7'", i<~>\n 



J. 42.— First three Branchia 

 the outer (convex) side of 

 set gill filaments (or leaflets 



I- (concave) side of the fin 

 gated processes (^^upportinj minul 

 tides of food, or other foieigu boc 

 chamber. 



i-IG. 42. 

 of Branchial Arches of a Perch, seen from 

 nml 4. basi-branchials : 5, hypo-branchials ; 



!>:.iM. Ill il , ; 8, styliform pharyngo-bran- 

 .11 , '. , 111 I'orior pharyngeal bone ; 9' and 

 -; . . 7, -lud 8, first branchial arch; 5', 



; A\. \\ . , I',". 7", and g', third branchial 

 h brancliiLvl ;irch ; 6"", fifth branchial arch. 



Arches from the left side of a Perch. On 

 nch branchial arch the series of closely- 

 be attached. " 



branchial arch are the scries of elon- 

 i denticles) which help to pre 

 es, passing from the mouth t^ 



responding pair of articular convexities or '' condyles." 

 Now in this matter the frog differs from both birds and 





Fig. 43.— Diagram of the changes undergone by the hyoid In a Frog In 

 passing from the Tadpole stage to the adult condition (couslrucccd from 

 Parker's Rlemoir). Uppermost left-hand figure, the youngest condition ; 

 lowest right-hand figure, the adult. //, the hyoidean arch, iilp.iin.itely 

 the corniculum ; b^ — 6^, the four branchial arches which become gradu- 

 ally atrophied, the cornua (or thyrohyal), ///being their representative 

 in the adult ; l'\ another branchial rudiment ; '-/;, the body of the hyoid. 



reptiles, every member of those classes possessing a 

 single median (occipital) condyle for articulation with the 

 vertebral column. 



Fig. 44. — Dorsal 



y lamellae behind 



Yet every member of the frog class, not only every toad 

 and newt, but also every species of the Ophiomorpha, and 

 even every one of the long extinct Labyrinthodons (with 

 the doubtful exception of the probably immature and 



