Newman.—Notes on the Physiology and Anatomy of the Tuatara. 231 
At the under surface of the jaw are small white scales, some partially 
others fully formed ; they partially overlap each other, as do shingles on a 
house roof. At the throat they are more largely and fully developed, and 
are of irregular shape, usually with many straight sides and rounded edges. 
_ Gradually these scales become arranged in parallel rows, the posterior edge 
of the front row overlapping the anterior edges of back ridge. On the’ 
abdomen these plates are much larger and more regular in shape (parallelo- 
grams) and are arranged in rows, each row being elosely bound by its 
anterior edge to an abdominalrib. About aninch from the transverse vent 
they become smaller, more irregular in shape, and the ends of the rows bend 
round, so that at the vent the rowsare indistinct. Behind the vent they are 
small, but soon grow larger, and then rows of straight-sided plates almost 
encircle the tail. These tail plates are longer and narrower, though as 
regularly placed as those on the abdomen. Under the throat the skin hangs 
in loose irregular folds. 
No sign of ears. Nostrils, two small holes almost hidden by lateral 
cranial skin ridges. These holes look upwards. A needle passed into them 
passes downwards and forwards—not backwards. 
Mouth 1-2 inches long, quite straight. 
Fore limbs shorter than the hind ones. Pes and manus have each five 
digits armed with sharp nails, curved like the teeth of a rodent. Pollux 
short and thick. Hallux slender and widely separated from other digits. 
Both pes and manus are large and covered on the under surface with small 
white scales. ` 
To the exhaustive description of the abdominal ribs given by Günther I 
cannot add anything, except a remark on a peculiarity which he noticed in 
one specimen. He examined six specimens ánd in one he found “a very 
curious anomaly as regards the union of the three bones of which the 
abdominal ribs consist ; they were united by joints.” This peculiarity existed 
only in the alternate ribs. This did not obtain in either of my specimens, 
which belonged to a different species. It is therefore probably a variation, 
and not a mark of a distinct species. 
Dentition. 
Dr. Giinther described specimens in all of which there were in each 
premaxillary bone a pair of incisors, far larger than any of the other teeth. 
These teeth were confluent at the base, and in old specimens when the cones 
were worn down, the incisor appeared as if a single tooth, resembling a ro- 
dent’s incisor. Dr. Knox, however, found that in one of his two specimens 
there were in each premaxilla three teeth, all confluent at the base; the other 
Specimen had but two cones. This newly discovered cone is nearer the 
middle line than the others. It is far smaller, slenderer, and sharper, and 
