188 MR. W. K. PARKER ON THE STRUCTURE AND 



the middle ; the fore part of its head is bent, adze-like. The facial pai't of the 

 maxillary is very high, so also, although lower, is the jugal part up to where it is 

 united, by suture, with the squamosal. 



The parasphenoid (pa.s.) is a very large, but truly Hyline, bone ; the foiu- rays all 

 run to sharpish angles ; the wide blade is swollen, and then rapidly attenuated ; the 

 guard is unusually wide, and the handle is a large, low triangle. The vomers (v.) are 

 perfectly typical ; they touch the sides of the septum, but not each other, and each 

 carries an oblique, oval, rather large, dentigerous boss. 



The difference between this skull and that of Hyla albomarginata can be seen 

 better by reference to the figures than by any description. This skull is about equi- 

 distant from that of the typical liana, and that of such a Neotropical Bufo as 

 B. ch'densis, or the Ethiopian B. i^antherinas ; it nevertheless keeps the Hyline 

 characters intact, whilst diverging less in some things from the norma than the species 

 of Hyla. The divergence of such a species as this from an oxydactyle Frog may have 

 been gentle and gradual ; there was no morphological stumbling-block to be got over 

 of any importance whatever. The likeness of this skull to the " norma" is as instructive 

 as its unlikeness. 



1. The whole skull is short, solid, strong, and deep ; and the osseous tracts of the 

 endocranium, altliough well, and almost normally, limited by cartilage, are remark- 

 ably Bufonine. 



2. The scidpturing of the very strong outer bones is another variation. 



3. The bones of the hind skull are anchjdosed above on the same side. 



4. The quadrate condyles have only partially retreated. 



5. The fontanelle is single, and partially open. 



6. There is a distinct prenasal rostrum. 



7. The septo-maxillaries are wanting. 



8. There is a wide post-palatine lobe. 



9. The horns of the annulus are wide apart, 



10. There is no proximal segment of, nor ascending jirocess from, the small columella. 



11. The stylo-hyal is confluent above, there is no hypo-hyal lobe, and the basal 

 plate is short, and has small lateral lobes. 



52. (B) Nototrcma marsupiatum. — Larva, 2^ inches long ; body, 1 inch ; tail, 1\ inch; 

 hind legs, 13 lines ; right fore leg free, \ inch long ; left fore leg still under the 

 operculum. South America. 



This skull is at a very important stage ; the larval structures are all present, and 

 the permanent structures are fast coming in. Its shape (Plate 30, figs. 10, 11), 

 now, is a short oval, for while the quadrate cartilage is where it was, right and left, 

 the cornua trabeculoe have dwindled down I'emarkably ; nevei'theless, aU the external 



