Vol 'i9']^ X ] Shufeldt, Anatomy of the Passenger Pigeon. 39 



tainty, what the balance of the morphology will be in any particular 

 case. It is always well, however, to make a careful comparison of 

 the skeleton in the case of all the genera of a family, and it requires 

 a comparative vertebrate morphologist, with a very vast and varied 

 fund of knowledge of his subject, to decide, in any instance, just 

 what amount of data to obtain, in the case of any particular species 

 to be anatomically investigated, when the entire morphology of a 

 typical representative of a closely related genus is known. 



If what I have thus far attempted to present of the osteology of 

 Ectopistes migratorius, and of the rest of the anatomy of that spe- 

 cies, — and knowing what he already knows of the morphology of 

 Columba livia and other pigeons, — will enable the ornithotomist 

 to surmise, perhaps with more than comparative certainty, what 

 the undescribed parts of the anatomy of Ectopistes migratorius 

 would reveal upon investigation, I feel that my researches have 

 accomplished all that I could hope for in this regard, with respect 

 to our now extinct Passenger Pigeon, and that my labor has been 

 well repaid. 



EXPLANATION OF PLATES. 



(All the figures in the Plates are by the author, and made, either by draw- 

 ing or photographic reproduction, direct from the subjects they depict.) 



Reference Lettering. 



aa. internal dermal margin of the auricular aperture. 



am. angle of mandible. 



c. complexus muscle (Figs. 2, 3.) 



cr. crop. (Figs. 3, 4 and 4.) 



ct. intestine cut away close to the external surface of the gizzard. 



dc. depressor caudae muscle. (Fig. 2.) 



e. eye. (Fig. 2.) 



el. internal view of eyelids. (Fig. 2.) / 



gp. gluteus primus muscle. (Fig. 2.) 



gz. gizzard. (Figs. 3, 4 and 5.) 



H. heart. (Figs. 3, 4 and 4.) 



hy. hyoid with muscles attached. (Figs. 2, 3, 4 and 5.) 



ks. keel of sternum. (Fig. 3.) 



