46 ON THE ANATOMY OF CERTAIN AUKS. [Jan. 18, 



longer and narrower than they are in B. marmoratus, and with 

 more pointed extremities. In S. nniiquus, too, the connecting band 

 of hepatic tissue, joining the two lobes at the back and above, is far 

 more extensive than it is in B. marmoratus ; I fail to find any trace 

 of a third lobe in either of these Auks. 



Both of these Murrelets possess a large pear-shaped gall-bladder, 

 Iving, in either case, beneath the inferior edge of the right lobe of 

 the liver. Likewise in each is the spleen well developed ; but this 

 organ in S. antiquus is long and subcylindrical in form, while in 

 B. marmoratus it is shorter, thicker, and of a decidedly pyriforni 

 outline. 



MacgiUivray gives us a very good description, illustrated by three 

 figures, of the proventriculus and gizzard of the Little Auk (Mer- 

 ffulus alle), winch appears in the eighth volume of Audubon's ' Birds 

 of America,' the royal quarto set. In the birds before me I fail to find 

 the band of " glandules," arranged as a belt at the extremity of the 

 proventriculus, at the entrance of the stomach. Nor is the oesophagus 

 so thiu as MacgiUivray found it to be in M. alle : in other particulars, 

 however, these Auks seem to be quite similar to it ; for I find the 

 inner coat of the elongated proventriculus and the lower part of the 

 oesophagus thrown into strong longitudinal rugae or folds, among 

 which the surface is thickly studded with minute openings, which 

 I take to be the mouths of the glandules. These rugae are con- 

 tinuous with similar, longitudinal elevations in the gizzard ; but in 

 this latter cavity they are covered by a closely fitting corneous 

 structure that readily peals off in the alcoholic specimens, leaving 

 the rugae in a condition precisely as we find them in tlie proventri- 

 culus and oesophagus. The gizzard and proventriculus are continuous 

 and but faintly marked externally by a constriction which shows the 

 ending of the latter and commencement of the former, while 

 internally, as I say, the definition is made quite sharp by the corneous 

 layer of the gizzard. The disposition of the muscles of this latter 

 organ are somewhat differently arranged from what MacgiUivray 

 gives us in his figure of M. alle. The tendon from which the fibres 

 radiated in the Murrelets above described is situated quite laterally, 

 and nearly opposite the pyloric exit of the pouch ; while in Macgilli- 

 vray's draw ing of the Little Guillemot, already referred to, this gastric 

 tendon is centrally located as we see it in Pigeons and other birds. 

 Both of my specimens had entirely empty gizzards, the cavities not 

 even containing a few grains of coarse gravel, which is not an 

 uncommon thing, I believe, in certain Auks. 



The intestines of these Murrelets present us with nothing worthy 

 of special remark, and I find a well-developed and large pancreas 

 present in each. According to MacgiUivray, in M. alle the rectal 

 extremity of the intestinal tube becomes much enlarged and quite 

 globular, while a short distance above it we find a pair of caeca of 

 no great size. Unfortunately an accident happened to these parts 

 in both of my specimens ; but I presume much the same arrangement 

 woidd obtain, as, so far as I know, all Auks are thus constructed in 

 regard to this part of their economy. 



If hereafter the differences I have pointed out are found to be 



