284 MR. G. GULLIVER ON THE [ May 12, 
ments of which neither the significance nor the importance is very 
obvious. Besides, in the current ‘ Anatomy of Vertebrates,’ the de- 
scriptions in this department are either so perfunctory or dogma- 
tically incorrect as to repel research. Thus we have no notice what- 
ever of the kind of muscular fibre composing the cesophageal sheath 
of any vertebrates, except when, in a comparison of this sheath of 
certain birds with that of ruminant mammalia (ii. p. 158, ni. p. 470), 
there occurs the singular notice that in this order the muscular fibres 
of the cesophageal coat ‘are of the striated kind.’”’ Hence the false 
doctrine might arise that the intimate structure of this muscular 
sheath is generally insignificant throughout the vertebrate subking- 
dom, and that the sheath of striated muscular fibre of the cesophagus 
in Mammalia is confined particularly to the order Ruminantia ; 
whereas the cesophageal sheath of ‘striped muscle is by no means 
confined in Mammalia to the Ruminants; for it exists more or less 
throughout the class, as well as in Fishes. Besides the Ruminants, 
several different orders or families of Mammalia have a sheath of this 
striated fibre extending all along the oesophagus to or even on the 
cardia, as may be well. seen, for example, in Rodents, Bears, and 
many others; while this avd of muscle in Man, Quadrumana, 
Felidze, the Horse, and several more Mammalia stops on the ceso- 
phagus much short of its cardiac end. ‘The comparison of the mus- 
cular coat of the cesophagus of Owls, and other Raptorial Birds that 
regurgitate their food in “castings,” with the corresponding sheath 
in Ruminants is erroneous; for this sheath is deficient in the striated 
muscular fibre in Owls and other birds, while striated muscle com- 
poses the chief portion of the coat of the cesophagus of Ruminants. 
Though numberless observations may be required to obtain and 
methodize all the facts, very easy and simple examinations will 
suffice for single diagnoses; just as, by an inspection of one part, we 
can arrive at the whole character of a plant or animal which had 
originally been determined by far more extensive researches. Con- 
stant differences in morphological arrangements are not the less 
important because we happen to be ignorant of their meaning. To 
define the exact value in taxonomy of the muscular sheath of the 
cesophagus requires far more extensive researches than I have been 
able to complete; but my observations show that it certainly 
affords valuable characters. 
Comparative anatomists have long since perceived many resem- 
blances between birds and reptiles; and of late Professor Huxley 
(Proc. Zool. Soc. 1867, p. 415 e¢ seg.) has so more particularly deter- 
mined the characters common to these two classes as to form them 
into his one great group of ‘Sauropsida.”” Accordingly he describes 
more exactly and comprehensively than had been previously done 
those points in which the two classes, constituting that one primary 
group, agree together and differ from Mammalia. But both he and 
his predecessors have neglected the cesophageal sheath, although it 
appears probable, from the observation cited above, that this pre- 
sents good characteristics. 
In short, in those observations the transversely striated muscular 
