538 SYSTEMATIC SYNOPSIS. — PICARIjE. 



possess in common. The sternum rarely conforms to the particular passerine model, its pos- 

 terior border usually being either entire or else doubly-notched. The vocal apparatus is not 

 highly developed, having not more than three pairs of separate intrinsic muscles ; the birds, 

 consequently, are never highly musical. There are some modifications of cranial bones not 

 observed in Passeres. Picaritp, like lower birds, usually lack a certain specialization of flexor 

 muscles of the toes seen in Passeres. This anatomical matter requires special attention, as 

 some important classificatory considerations are involved. The jjasserine rule is, that the 

 flexor liallucis, which bends the hind toe, is perfectly distinct from the flexor perforans, which 

 bends all the other toes ; and that the former has but one tendon, going to hind toe, while 

 the other has three tendons, going to all the rest of the toes. Passerine birds being considered 

 to represent the "normal" (or usual) arrangement, are called nomopelmous ; and all birds 

 which do not have this arrangement I call anomalopelmous. Passerine birds are also called 

 schizopelmous, with reference to the complete separation of the hallucal from the other dig- 

 ital tendons. But the anomalopelmous Picarian birds present several further specializations 

 of the arrangement for bending their toes. In the Hummingbirds the flexor hallucis besides 

 going to the first toe supplies also the second digit by a branch, and sends in addition the 

 rudiments of little slips to the third and fourth digits. In the Hoopoes the arrangement 

 is nearly schizopelmous, but there is a desmopelmous feature beyond the bases of the 

 toes. In the Cuckoos, again, the tendons of the flexor hallucis and flexor perforans are 

 connected by a vinculum or ligament at the point where they cross each other on the way 

 to their respective digits ; they are hence called desmopelmous, and this arrangement is also 

 shared by psittacine and gallinaceous birds. Again, in the Swifts and Goatsuckers, of the 

 group Cypseliformes, the respective tendons of these two muscles are extensively blended to- 

 gether ; they are hence termed sympelmous. Fourthly, in numerous zygodactyle birds, the 

 Woodpeckers and their allies, the flexor perforans has only one tendon, which goes to the 

 " middle" or third toe, i. e. the outer anterior one, while the flexor hallucis splits into two 

 or three tendons, which supply all the other toes ; tliey are hence termed antiopelmoiis. Fifthly, 

 in the Trogons, which are yoke-toed in a diff"erent way from any other birds, by reversion of 

 the second instead of fourth toe, the flexor hallucis has two tendons which supply the two hind 

 toes, and the flexor perforans has likewise two tendons, for the front toes ; they are thus what 

 is called heteropelmous. The technical terms here used of the birds themselves are equally ap- 

 plicable to the anatomical arrangements ; one may speak, for example, of anomalopelmous feet, 

 or anomalopelmous tendons, as well as of anomalopelmous birds. Three of the five arrangements 

 noted for Picarian birds, the sympelmous, antiopelmous, and heteropelmous, are peculiar to 

 this group. With regard to the ambiens muscle, it is absent in most Picarice, which are there- 

 fore anomalogonatous ; but present in the homalogonatous Cuckoos and their near relatives the 

 Turacous. Externally, the feet are very variously modified; one or another of all the toes, ex- 

 cept the middle one, is susceptible of being turned, in this or that case, in an opposite from the 

 customary direction ; the fourth one being frequently capable of turning either way; while in 

 five genera of Picidce and one genus oi Picumnidce the first, and in two genera oi Alcedinidce 

 the second, toe is deficient. When all four toes are turned forward, as in the Colies, the feet 

 and their owners are termed pamprodacti/lous. When there are three in front and one behind, 

 as in Kingfishers, the term anisodactylous is used ; and when the digits of such a foot are 

 extensively soldered together, the formation is called syndactylous. In some cases, as the 

 family Microj)odid(B or Swifts, some members of it are pamprodactylous, others anisodactylous. 

 A very frequent arrangement is that of toes in pairs, two behind and two before ; most such 

 yoke-toed birds have the properly zygodactylous arrangement, by reversion of the fourth or 

 outer toe, as in the Woodpeckers, Cuckoos, and others; but in the Trogons alone the second 

 or inner toe is the reversed one, and the arrangement is styled heterodactylous. The tarsal 

 envelop is never entire behind, as in the higher Passeres. Another curious peculiarity of the 



