Bulletin of the Geological Society of America . ind the internal nares. There is certainlya long interspace between the basisphenoid and the vomers and this spaceis occupied by the pterygoids. Therefore I can not adopt the interpreta-tion of the paired vomers being in fact the parasphenoid. On the con-trary, the true parasphenoid is present in the major portion of therostrum basisphenoidei. It is useful also to compare the sections givenby Sollas. It is quite true that the parasphenoid may extend for aconsiderable distance anteriorly and that the vomer may extend farposteriorly, but the main r
Bulletin of the Geological Society of America . ind the internal nares. There is certainlya long interspace between the basisphenoid and the vomers and this spaceis occupied by the pterygoids. Therefore I can not adopt the interpreta-tion of the paired vomers being in fact the parasphenoid. On the con-trary, the true parasphenoid is present in the major portion of therostrum basisphenoidei. It is useful also to compare the sections givenby Sollas. It is quite true that the parasphenoid may extend for aconsiderable distance anteriorly and that the vomer may extend farposteriorly, but the main region of the parasphenoid is below and imme-diately in front of the basisphenoid, and the main region of the vomer THE IMPORTANT FACTS 461 is in the neighborhood of the nasal capsule^ originating on the ventralside of the paraseptal cartilage. The vomer in Dicijnodon certainly ap-pears to be a paired bone, and its relationships are like those in themammals. The rostrum of the basis cranii I could not imagine as beingthe mammalian vomer. MTrCfi. Figure 2.—Dicynodon sollasi Broom from below. Natural size. Bo = Basioccipitale. Bs = Basisphenoid. Ch = Internal nares. Eo = Exoccipitale. Ep = Epipterygold. F. c. = Foramen carotidls. F. p. = Foramen parietale. F. V. =: Fenestra vestibuli. F. V. = Foramen vagi, etc. J = Jugale. I. Pt. := Interpterygoidal space. L = Lacrymale. M = Maxilla. N = Nasale. Opo = Opisthoticum. P = Parietale. Pa = Parasphenoid. PI = Palatinum. Pm = Prsemaxilla. Po = Postorbitale. Pof = Postf rontale. Prf = Prsef rontale. Pro = Prooticum. Ps = Praesphenoid. Pt = Pterygoid. Q = Quadratum. Qj = Quadratojugale. Sm = Septomaxillare. Sq = Squamosum. T. Bo. = Tuber basioccipitale. Tr. = Transversum. V = Vomer. Z = Tooth. The distribution of the bones on the ventral side of the skull ofDicynodon (and also of all Theromorpha) does not differ greatly fromthat of the same region in the later reptiles, the Archosauria, as well asin the Stegocephalia and also in the mamm
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