522 E. TULLEY NEWTON ON THE REMAINS OF 



EXPLANATION OF PLATE XXII. 



(All the figures on this Plate are reduced one-half linear, "except figs, la, lb, 

 8 a, 8 b, 8 c, and fig. 15, which are otherwise marked. The dotted outlines 

 simply indicate probable restorations, except in the case of fig. 3.) 



Portheus gaultinus, n. sp. 



Fig. 1. Outer surface of left lower jaw, hyoid, &c. The teeth which are pre- 

 served in the specimen are shaded in this figure ; those which have 

 been broken are restored in outline ; den, dentary ; art, portion of 

 articular ; ch, ceratohyal ; qu, part of quadrate. This figure has been 

 reversed in order to make it correspond with fig. 2. 

 \a, lb. Two teeth viewed from behind to show the incurved points. Natural 

 size. The outlines placed beside these, to show their oval form in 

 section, are a little too large. 



2. Outer surface of right upper jaw, with ethmoid &c. in their natural 



positions. Teeth restored in outline, as in fig. 1 : pmx, praemaxilla ; 

 mx, maxilla ; ju, jugal ; pi, palatine ; pr.fr, prefrontal ; eth, ethmoid ; 

 olf, perforation for olfactory nerve. 



3. Bones of ethmoid region seen from below : eth, ethmoid ; mx, fragment 



of anterior articular process of maxilla, which is lodged in a deep ex- 

 cavation of the ethmoid ; prfr, these letters point to the surface of the 

 prefrontal, which articulates with the palatine ; vo, anterior portion of 

 vomer (?) 



4. Outer surface of right side of brain-case: bs, upper portion of basi- 



sphenoid ; a s, alisphenoid ; pa, parietal region ; p s, presphenoid ; 

 fr, frontal ; sp.ot, sphenotic (postfrontal) ; pr.ot. prootic ; op.ot, opis- 

 thotic or exoccipital ; ob, supraorbital (?). 



5. Inner view of left lower jaw with hyoid &c. in situ : den, left dentary ; 



ch, right ceratohyal ; hh, hypohyals ; cl, cV , portions of clavicles ; 

 bh, basihyal. 

 f>. Front view of the symphysial surfaces of the two mandibular rami. 



7. Mandible seen from above, with the hyoid bones between the rami : den. 



left dentary ; ch, ch, ceratohyals ; hh, hh, hypohyals ; bbs, basibranchi- 

 ostegal ; pt, pterygoid ; qu, quadrate. 



8. View of left side of basibranchiostegal ; a, b, c show the positions of the 



plates enlarged in the next three figures. This figure is unfortunately 

 placed upside down. 



8 a. Portion of one of the plates with ridges and grooves, enlarged 7 

 diameters. 



8 b. One of the radiating pitted plates, enlarged 10 diameters. 



8 c. A small portion of another pitted plate, with minute teeth in situ, en- 

 larged 45 diameters. 



9. Right and left maxillee and prasmaxillae seen from below, the two sides 



in their natural relation to each other. 



10. Side view of five dorsal vertebras, showing the bases of the neural 

 arches, the lateral depressions, and the enlarged heads of the ribs. 



11. The thh-d vertebra of fig. 10, seen from behind. 



12. Section through another dorsal vertebra, seen from above : a and p, 



anterior and posterior concavities ; / d, lateral depressions. 



Portheus Daviesii, n. sp. 



Fig. 13. Outer surface of upper jaw &c. : mx, maxilla, the hinder part broken ; 

 art, surface of maxilla for articulation with prasmaxilla ; v, vertebra ; 

 p.cl, postclavicle or ventral spine. 



