552 



NATURE 



[October 2, 1890 



The same is true of Mastodonsaurus giganteus, although 

 that form is succeeded by a closely allied species in the 

 proper Keuper ; the latter species, by the way, being not im- 

 probably the one occurring in the Bristol Rhastic, which 

 was identified by the British Association Committee with 

 M . gig«nttus^ Ps.' table, with the names of the forms 

 characteristic of each horizon, fully explains the author's 

 views on all these points of geological classification. 



Passing to the descriptive portion of the work, we may 

 first of all observe that Dr. Fraas sees no reason to 

 depart from the generally accepted homology of the 

 bones forming the hinder part of the Labyrinthodont 

 cranial roof; and he does not, therefore, accept the- 

 view of Dr. Baur that the bone usually termed the 

 squamosal {Sq. of figure), is really the supra-temporal, and 

 vice versa; neither does he adopt the suggestion of the 



t 



^V\\\\oi Mastodonsaurtts giganteus, Qnz-^ii}a.TiaX.\ir3S.%\zs. S.Occ, supra-occipiial ; Ep., epiotic ; P., parietal; Sq^, squamosal ; S.Temp.. supra-temporal ; 

 Pt.F., post-frontal; Pt.Orb., post-orbital; F., frontal; Pr.F., pre-frontal ; N., nasal; P.Mx., pre-maxiUa ; Mx.sup., maxilla; L., lachrymal; 

 7a.,jugal; (P.^'w., quadrato-jugal. 



same palaeontologist that the bone usually termed epiotic 

 {Ep) really represents the opisthotic of other Vertebrates. 

 The arrangement of the Labyrinthodont cranial bones is 

 well shown in the woodcut of the skull of Mastodonsaurus 

 given on p. 44 (reproduced here), in which we notice 

 that the squamosal has a more rhomboidal form given to 

 it than in the restoration published by the British Associa- 

 tion Committee in 1874. 



NO. 1092, VOL. 42] 



Of the several species described, the first is the well- 

 known M astodonsaurics giganteus, of the Muschelkalk 

 and Lettenkohle, of which the author gives a new figure 

 of the fine skull found in the Lettenkohle of Gail- 

 dorf in 1833, and so well known in all Museums by 

 means of plaster-casts. This magnificent specimen, we 

 learn, has recently been thoroughly cleaned from matrix, 

 by which means the true relatior^s of the bones can -;be 



