^"'loi'^^'] Shufki.ot, Osteoloiiv of Hai-yis's Corinorani. C^y 



J2ikI and .Jjicl. so that this rci^ion ot thi' wholr satiuni contains 

 one more vertebra than other Cormorants. Ww loUowing post- 

 sacral, caudal, and pygostyle vertebrae exhibit no more than, or 

 rather as much, individual variation in numbers and connections 

 as other species. The pygostyle begins with the 48th vertebra — 

 in one specimen apj^arently with the 49th — but it is, unfortunately, 

 not possible to determine how many vertebras have been fused 

 into the pygostyle. It is possible that the additional vertebra 

 contained in the presacral complex of the sacrum, and thus 

 lengthening the whole pelvic region, accounts for the unsatis- 

 factory results which we arrive at by comparing the proportions 

 of length of pelvis to the bones of the hind limbs of P. harrisi with 

 other Cormorants." 



As stated above, I have at this time five pelves of Harris's 

 Cormorant at hand, and they present similar differences, due to 

 individual variation, that Dr. (iadow found to obtain in his three 

 specimens. 



In all five of the skeletons belonging to the collections of the. 

 U.S. National Museum (Nos. 19,628, 19,719, 19,720, 19,721, and 

 19,722) it is the 24th vertebra that is the first of the spinal 

 column which fuses with the iha in the formation of the pelvis. 

 It is the anterior one of the series that forms the pre-acetabular 

 vertebral part of the pelvis, which terminates at the anterior 

 peripheries of the acetabulae. These are easily counted, for their 

 transver.=e processes, abutting against the ventral surfaces of the 

 ilia, are in plain sight. 



Dr. Gadow, as just stated, found the 29th vertebra to form 

 " the last pre-acetabular buttress," and so it does in Nos. 19,628, 

 19,721, and 19,722 of the specimens here being considered ; while 

 in Nos. 19,719 and 19,720 it is the 30th vertebra that does so, 

 instead of the 29th. Then follow two more, in which the trans- 

 verse processes have been almost entirely aborted. These two 

 vertebrae are directly between the acetabulae ; their centra are 

 large, and the spinal canal, as it passes through them, is at its 

 maximum calibre for this part of its continuity. In No. 19,719 

 and 19,720 these two vertebras are the 31st and 32nd, while in 

 the other specimens they are the 30th and 31st. Next follow two 

 vertebrae which are the true sacral vertebra. In Nos. 19,719 and 



19.720 these are the 33rd and the 34th, while in the remaining 

 three specimens they are the 32nd and 33rd. 



If we reckon the last uro-sacral vertebra to be the last one that 

 fuses with the pelvis, then in No. 19,719 this vertebra is the 42nd ; 

 in No. 19,720 it is the 43rd ; in 19,628 it is the 40th ; while in Nos. 



19.721 and 19,722 it is the 41st. 



This is rather a remarkable variation, and I could scarcely 

 believe it until I had made the count with the greatest possible 

 care several times over. 



No. 19,719 has 7 vertebrae plus the pygostyle in the skeleton of 

 its tail (43rd-49th + P.) ; No. 19,720 has 44th-48th + P. ; but I 

 am inclined to believe that the last caudal vertebra has been lost 



