DEVELOPMENT OF THE SKULL IN THE BAT EACH I A. 
197 
This bar is very slender all the way to the basal plate, but it has a small hypo-hyal 
lobe (Plate 15, fig. 9, c.liy., h.hy.) ; the front open space between the hypo-hyals is less 
than the basal plate, which has no front lateral lobes, has sharp hinder lobes, and 
normal thyro-hyals (t.hy.). 
The mandible (fig. 9) is long, sinuous, and very similar to that of Pelodryas, having 
a large mento-Meckelian and a low coronoid process ( m.mk ., ar.). 
The investing bones are very similar, on the whole, to those of the last kind; the 
fronto-parietals {/■£>■) scarcely meet behind; they have the same divergence forwards, 
and cover a little more of the fontanelle. 
The nasals (n.) are twice as large; they have a greater surface to cover, and they 
do this better; yet much cartilage is left naked; their form is normal. The pre- 
maxillaries (px.) are almost transversely placed across the narrowed truncated snout; 
both then nasal and palatine processes are normal. The maxillaries are of the 
average strength and size, the ascending facial plate is enlarged and rough under the 
point of the nasal. Under the nostril there is a rough suborbicular septo-maxillary 
(fig. 9, s.mx.) ; it is notched in front. 
The quadrato-jugal (q.j.) is slender, but it is well united with the quadrate. The 
squamosal (figs. 7, 9, 11, sq.) is a large T~ s baped bone, with its upper bar diverging 
forwards, and scooped outside for the annulus ; its descending or main bar is unusually 
long, and of a good width. The parasphenoid {pa. si) is only two-fifths the length of 
the skull, but its main paid is broad; it is but little convex (fig. 9); its processes are 
all pointed, and the basi-temporals are slender. The vomers (v.) are much less than 
in the last, and yet not small; their form is very peculiar. They are a wide distance 
apart, and diverge rapidly forwards; their main part is a long oblong, and ends behind 
in a transverse toothed part, which has a triangular elevation. There is no post-narial 
spike, but the pre-narial spike is forked, and the proximal part of this external 
process is almost notched off from the body of the bone ; the outer fork is the longer 
of the two. The shorter hind spike would appear to be the homologue of the ordinary 
post-narial process, and the whole bone is evidently dislocated forwards through the 
hypertrophy of the trabecular nasal floor (, s.nd .). 
Long as these vomers are, they are half their own length both from the front of 
the snout and from the fore edge of the girdle-bone. 
The dentary (fig. 9, d.) is slender, and ends in the middle of the ramus. 
Here we have an assemblage of characters which, in the aggregate, put this type far 
away from the “norma,” and yet most of these differences are in reality gentle modifi¬ 
cations of a Ranine skull. 
1. The cranial cavity is both short and shallow. 
2. The auditory capsules are small, but have a huge tegminal parotic growth. 
Urodeles ( Menopoma , Siren , Gryptobranchus, &c.) the epi-hyal becomes fused with the quadrate. In 
Proteus it is large, very similar to that of a Shark, and remains free. 
