18C1.] MR. A. D. BARTLETT ON THE BAL.ENICEPS. 131 



The Saltator isthmicus may be distinguished from the Trinidad 

 bird by the less pure white on the throat and belly, the more regular 

 flammulations of the lower surface, and its uniform black bill. The 

 Bogotan {S. striatipectus) is much darker on the breast and head, 

 and has much less olivaceous in its coloration. The point of the 

 bill is, likewise, pale in the latter bird. 



7. On the Affinities of Bal^eniceps. 

 By a. D. Bartlett. 



On appearing before you this evening with new evidence of the 

 affinities of this bird, and in endeavouring to aid in settling a subject 

 so long disputed and frequently discussed, I beg to refer, first, to 

 the elaborate and carefully written paper by Mr. Parker, in which 

 this bird, after the most careful examination and comparison of its 

 bones, is considered to be an Ardeine. 



I have, then, to observe, that from an entirely different course of 

 examination, and by the consideration of its other structures, I have 

 arrived at the same conclusion ; and I hope, with the assistance of 

 my friend Mr. Stewart, to prove to the satisfaction of our ornitho- 

 logical friends, that there is no longer any doubt in the matter. 



The death of the survivor of the two birds brought home by 

 Mr. Consul Petherick has afforded me the opportunity of making a 

 more accurate examination of its structure, and this has led me to 

 the discovery of two remarkable powder-down patches which, it will 

 be remembered, I stated on a former occasion * I had failed to find 

 in the living bird. 



Upon removing the skin from the body of this bird, I was so struck 

 by its close resemblance to the Herons, that I immediately killed a 

 Heron and removed its skin also, in order to form a fair opinion by a 

 close comparison of all the parts of these two birds. The exact 

 form of the body and limbs was most remarkable ; the structure of 

 the hind toes (upon which so much stress has been laid) was alike, 

 these turning backwards, forwards, or sideways in both species. The 

 head and neck, however, oi Balcsniceps, when compared with the same 

 parts of the Common Heron, present some very considerable differ- 

 ences. These differences consist, first, of the much larger head, and 

 consequently stronger neck, in Balaniceps as compared with the 

 Heron. Doubtless these modifications have reference to the food and 

 the mode of obtaining that food. Many illustrations can be found 

 of similar modifications ; I may refer to one in the group under con- 

 sideration, which results from the comparison of Cancroma with 

 Eurypyga, and which presents, perhaps, the most extreme modifica- 

 tion in the form of the bill in two birds of the same family. 



As far as I was able to examine the viscera of the Balceniceps, I 

 could discover nothing that would lead me to doubt its Ardeine 

 affinities ; the stomach, liver, intestines, &c., of the two birds ap- 

 peared exactly to correspond in structure and arrangement. 



* SeeP.Z.S. 1860, p. 461. 



