LIMIOOL^ 



353 



is present in Larus argentatus, marinus, and glaucus, not 

 in fuscus. It is absent in Sterna and Lestris; present in 

 Anous ; absent again in Bhynchops. 



The biceps is peculiar in some members of this family. 

 In Larus, Sterna, and Anous the biceps has, as usual, the 

 two heads, humeral and coracoidal ; but they form two per- 

 fectly distinct muscles, of which one, the coracoidal, soon 

 divides into two distinct muscles again, which are inserted 



Pio. 172. — Tensobes Patagii of Larus argentatus (AriEE Beddakd 



FBOM FOKBES). 

 n, osseous nodule. Other letters as In fig. 171, 



respectively upon the radius and ulna. The biceps head 

 goes to the radius, and as a rule gives off the biceps slip to 

 the patagium ; but in Larus ridibundus, according to FiJE- 

 BEINGBE, this slip arises from the coracoids, an anomaly 

 observable also in the petrel, Thalassiarche. Bhynchops 

 has no biceps slip at all. 



The anconcBus is generally attached by a tendon to the 

 humerus. 



A A 



