480 PROF. G. GULLIVER ON [June 15, 
Osmerus, in which the corpuscles are much smaller than in certain 
Apodes. The smallest corpuscles occur in some of the little species 
of Acanthopteri and Anacanthini, and in the Sprat and Herring, 
while their congener the Pilchard has slightly larger corpuscles. 
They are somewhat larger in the river-Eels than in the Conger. In 
no single order of fishes are the corpuscles twice as large in one spe- 
cies as in another; they are quite as large in the osseous Salmon 
as in the cartilaginous Sturgeon, and in the Sharks and Rays so 
much larger as to adumbrate a distinct class. Lepidosiren has the 
corpuscles of such still greater magnitude as to depart in this respect 
from any regular fish to reach the saurobatrachian character. 
BaATRACHIANS. 
Form and size of the corpuscles.—On each broad surface they are 
generally flat or somewhat vaulted; and their outline is regularly a 
well-defined oval figure, mixed occasionally with a few of a suboval 
or even circular shape, as indeed is the case among all regularly 
elliptical blood-disks, though this is rarer in Birds than in the lower 
classes and in the Camels. In Batrachians, the short diameter of 
the corpuscle being taken as 1, its long diameter would vary com- 
monly between 14 and 1?. The thickness of the corpuscle is about 
one third of its short diameter ; and the nucleus may be either sub-- 
rotund, or more commonly liker in shape to the envelope. The 
largest red blood-corpuscles of Vertebrates occur in the tailed Batra- 
chians, of which Amphiuma, a cauducibranchiate species, has the 
largest of all, so that these are visible to the naked eye, and the 
perennibranchiate Proteus the next in size; and in Sieboldia, which 
has deciduous gills, the corpuscles are larger than in Siredon, which 
has permanent gills. In Amphiuma and Proteus the corpuscles are 
at least thrice as large as in some Frogs and Toads—an amount of 
difference of which there is no example either in the class of Birds 
or Reptiles, though it is exceeded among Apyreneemata. The cor- 
puscles in the anurous Batrachians are not always bigger than, and 
sometimes not so long as, in a few reptiles and in some Sharks and 
Rays. The size of the corpuscles in Batrachians may differ in the 
same individual at different seasons. A few more observations on 
the corpuscles in this class are given in the ‘ Proceedings of the 
Zoological Society,’ Feb. 4, 1873. 
REPTILES. 
Form and size of the corpuscles.—They are oval, flattish, little 
tumid on each broad surface—much of the same shape as, but gene- 
rally rather longer in proportion to their breadth than, in Batrachians, 
as is the case, too, insome birds. Andas in such elongated shape of 
the corpuscles in a few species (e.g. Anguis fragilis and Crocodilus 
lucius, Syrnea nyetea and Columba migratoria) Reptiles and Birds 
agree, so they differ from the other classes. Of Reptiles the largest 
corpuscles occur in some Crocodiles and Tortoises, and the smallest 
in the little Saurians and larger Teiws and Monitor; the reptilian 
corpuscles are smaller than those of the batrachian Urodela, but in 
