1875. ] RED BLOOD-CORPUSCLES. 485 
Mammal. It would be very interesting and probably instructive to 
examine the corpuscles of the Sirenia. 
Reverting summarily to a few points throughout the whole apyre- 
neematous class, we shall find several plain facts which, though long 
since demonstrated, are still ignored iu the current treatises of com- 
parative anatomy and histology. For example, while the smallest 
corpuscles occur in the Ruminants, there’ are some species of this 
order in which the corpuscles are larger than in certain Fere ; the 
Edentates, on the other hand, are eminently characterized by the 
largeness of the corpuscles; commonly the diameters of the apyre- 
neematous corpuscles agree remarkably with the short diameters of 
the corpuscles in Birds. The corpuscles in a few Apyrenemata are 
five times as large as in others; and even in the single order of 
Ruminants the corpuscles, besides aberrations in their shape, are 
thrice as large in several Cervidee and Bovidee (fig. 35) as in some 
Tragulide (figs. 29 and 30). In the Feree the corpuscles are more 
than twice as large in some species as in others, in this order the 
largest corpuscles (fig. 14) being larger than those of Man (fig. 1), 
and the smallest (figs. 18 and 19) smaller than in some Ruminants 
(figs. 35 and 36). Hence, on the whole, there are greater diversities 
in the size of the corpuscles than in any other class ; so that in this 
point of view a single apyrenzematous order would appear equal to 
an entire class either of Birds or Reptiles, and each of these two pyre- 
neematous classes only equivalent to an order of Mammalia. But com- 
paring the largest with the smallest batrachian corpuscles, and those 
of Lepidosiren and some Rays and Sharks with the smallest corpuscles 
in osseous fishes, differences of size appear almost or quite as great 
as in Apyrenzemata. 
From this class selections might be and have been made to show 
that there is no relation between the size of the species and the size of 
the corpuscles. These are quite as large in the tiny Harvest-Mouse 
(fig. 46) and Shrew (fig. 10) as in the great Giraffe (fig. 36) and 
Horse (fig. 26). But if, instead of thus comparing such widely 
different animals, and excepting some little irregularities already 
noticed, we confine the observations to small natural groups of the 
class, such a relation will plainly appear in a rule that the largest 
corpuscles occur in the large species and the smallest corpuscles in 
the small species of a single order or family. This relation is well 
shown by the Ruminants, Rodents, and Edentates ; and even in the 
Ferze, which offer some exceptions, the largest corpuscles are found 
in the big Seals (fig. 14), and the smallest corpuscles in the little 
Viverras and Paradoxures (figs. 18 and 19). In fine, though this 
rule is applicable only to single orders or lower sections of Apyrenze- 
mata, it extends to the whole class of Birds, but neither to Reptiles, 
Batrachians, nor Fishes, except in some partial instances, which seem 
to be rather indeterminate or accidental than regular. 
In the following Tables the measurements are all in vulgar fractions 
of an English inch, and express only the average diameters of the red 
blood-corpuscles or their nuclei. The numerator, being invariably 1, 
