Genus— M ESOCARBO. 
Mesocaebo Mathews and Iredale, Ibis 1913, p. 415 . . Type M. ater. 
Small Phalacrocoraeine birds with comparatively short, slender bills, rather 
short necks, long wings, and medium tail composed of twelve feathers. 
The bill is more delicately formed than in the preceding genus, but on 
exactly the same pattern. 
The tail is about three times the length of the culmen or metatarsus, 
which are subequal, and more than half the wing length. 
When Iredale and I separated this form (loc. cit.) we wrote : “ The 
species of Mesocarho differ from those of Hypoleucus in their shorter and more 
slender bills, their longer tails and more slender build: from those of 
Microcarho in their longer and proportionately more slender bills as well as 
their proportionately shorter tails.” 
All these genera agree in having twelve taU-feathers, whereas Phalacro- 
corax has fourteen. The taxonomic value of this difference is uncertain, 
as the only recent systematist to study the group as a whole placed no 
value upon any of the characters used by himself in determining genera in 
other groups, and his species, subspecies, and genera have little interest to 
any worker save himself. This is unfortunate, as each worker cannot 
undertake a monographic review of a family such as this one to exactly 
determine the few forms he has personally to deal with. 
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