232 
MR, W. K. PARKER OK THE STRUCTURE AND 
The vomers (v.) are very small shells, bihd behind, and protecting the circular inner 
nostrils ( i.n .), which are wide apart. 
Very much of what is peculiar in this skull may be summed up in the word 
“arrested;” but to this general character must be added such things as are not often 
seen even in young specimens of higher kinds :— 
1. There is a small basioccipital, and a persistent cranial notochord. 
2. The prootics and ex-occipitals are continuous on the same side. 
3. There are no secondary fontanelles. 
4. The optic fenestra is very large. 
5. The girdle-bone is arrested, and there are three rudiments answering to the 
lateral and perpendicular ethmoids. 
6. The palato-suspensorial arch goes no further back than the postorbital region. 
7. The pedicle is not absorbed above. 
8. The palatine bone is a mere thread. 
9. The Eustachian opening is nearly closed. 
10. There is only a ligulate, imperfect annulus. 
11. There is no columella, 
12. The mento-Meckelian rods and the condyles of the mandible are very large. 
13. The hyo-branchial plate has its processes feebly developed, as in a young 
Common Frog 1 or Toad. 
I shall take the liberty to modify Dr. Gunther’s classification, somewhat; but I see 
no advantage in bundling together several of these groups—as Professor Mivart has 
done (Proc. Zool. Soc., 1869, p. 289). 
Diplopelma might go with Engystoma and help to form the “ Engystomidoo.” 
Dr. Gunther himself (“Bat. Sal.,” p. 50) says that in Diplopelma the toes are only 
“ one-third webbed,” and in Engystoma free (p. 51). Moreover, the columella is well 
developed in both these genera, whereas in Rhinoclerma it is a mere rudiment. The 
author says of another member of his “ Ith in o dermati d se, ” viz. : Atelopus, “ I have 
never seen the animal” (note to p. 48), and of another genus— Uperodon —that “the 
tympanum is hidden;” and his description of the skull (p. 49), although short, is 
enough to show that it is very similar to that of Hylaplesia, and extremely unlike 
that of either Rliinoderma, or of the species of Diplopelma, or that of Engystoma, 
soon to be described. 
By their skulls these small species must be judged, not keeping out of sight other 
characters, especially the suppression of the clavicula (“pro-coracoid”), and of the 
manubrium sterni (“ omosternum ”).* 
I shall follow Dr. Gunther’s example and limit the next group to the one genus 
Phryniscus (see “Bat. Sal.,” p. 42). 
* These pro-coracoids and omosternums are absent in Engystoma, Gallula, and Diplopelma (Mivart, 
Proc. Zool. Soc., 1869, p. 289). 
