DEVELOP^MEXT OF TITE SKFLL IN THE BATRACHIA. 221 



shows a large triradiate upper part, and a long (deep) sinuous preopei'cular process 

 bound by the "orbitar process," behind. The parasphenoid (fig. 6, pa.s.) is unlike 

 that of the last, it is shortened in front and is there made up of spines; its basi- 

 temporal wings are very long, and the pterygoids bind over them so as to cut away 

 tlieir fore edge, outside ; they then run to a point, almost as far as the Eustachian 

 openings {eit.). The hind part is a broad triangle, and in front of it the middle of the 

 bone is raised into a triangular apophysis, which looks forwards. The vomers (v.) are 

 formed of three curved rays, the two hinder rays half surround the inner nostril (in.) 

 and the front ray curves in the other direction. 



63 (continued). — (B) Otiloplius margaritifer . — Adult female ; 2f inches long (Hyrtl's 

 prepn., Mus. Coll. Surg., Eng.). Brazils. 



This skull, kindly lent to me by Professor Flower, shows to what a degi-ee of 

 external modification the Bufonine type may undergo without losing any essentially 

 Anurous character. 



In the side view (Plate 38, fig. 1) we see that the height of the squamosal, measured 

 at right angles to the basis cranii, is equal to the gape; in Rana pipiens and Cystig- 

 nathus ocellatus, it is only one-third ; and that is the normal proportion. 



This is due to two things — to the height of the lateral crest of the squamosal, and 

 to the depth of the grooved sigmoid pre-opercular region (figs. 1, 2, sq.) ; it is the 

 upper part which has developed so largely since the creature was half grown (see 

 fig. 3, sq.). 



The endocranium is now completely ossified behind (fig. 2) ; but even now half the 

 orbital region is cartilaginous (fig. 1, o.s.) ; this part is extremely shallow. The sides 

 of the skull are raised all along up to the snout, and the nasal, frontal, and squamosal 

 crests {n.,f.p., sq.) are all frosted with small bony spikes and knobs ; the latter crest, 

 as a large " eai'," reaching further backwards than the occipital condyle. 



Behind (fig. 2), the parietal part of the roof-bones (f-p.) has lost the suture, and 

 the whole plate lies flat across the wide audito-occipital region, partly covering the 

 epiotic eminences (ep-)- Where the squamosals join the roof-bones there is a con- 

 siderable valley, on each side, in the hind skull. The mid skull and the nasal region 

 are concave. 



The orbital part of the squamosal (fig. 1, sq.) projects but little from the shaft, only 



reaches half way to the jugum, and points towards the hind part of the facial plate 



of the nasal («.). The nasal, frontal, and squamosal form three-fourths of an orbital 



ring, which is finished by membrane, below, far above tlie edge of the maxillary [mx.) ; 



all the edges are produced or limbate, and concave. A little more ingrowth of the huge 



nasal would have made it equal to the prefron to -nasal of the Chelonian. The pre- 



maxillary is a strong bone like a phalangeal segment, and is nearly all nasal process ; 



its top carries the valvular labials («./'. »./-.") Behind this bone, in an interspace formed 



• In fig. 1 the second labial is lettered u./V by mi.stake, and the line from u.P. points to a part of the 

 nasal wall. 



