86 PTERYLOGRAPHY. 



number of rectrices is less variable ; it is certainly more uniformly divided between ten and twelve 

 than in the Passerina?. I find twelve in Coracias, Prionites, Mcrops, GaJbuJa, Todus, Leptosomus, 

 Prodotes, Troy on, Capita, Monasles, Pirns, Yunz, Psittacus, and Akcdo ; and ten in Cypselus, 

 Trochilus, CaprinmJffits, Cuculus, Centropus, PhtsnicopJiancs, Scytltrops, Crolopliaga, Bttcco, Micro- 

 pogon, Pogonias, Eliampliastus, Buceros, Upitpa, Coliits, Musopluif/a , and Opisthocomus. 



1. MACROCIIIRES. 



In this family I place the two genera Cypselus and TrocMl/ts, which, indeed, present but little 

 external similarity, but are very nearly allied in the structure of their wings. The form of the 

 feather-tracts also justifies this union, although there are some pterylographic differences. Both 

 have a distinct, downy aftershaft, which is larger in Cypselus than in TrocMlus. In neither of them 

 are there down-feathers among the contour-feathers ; but Cypselus has distinct dark gray down on 

 the spaces of the trunk, which does not occur in TrocMlus. Moreover, the broad bands of the 

 inferior tract, uniformly narrowed from before backwards without any trace of an outer 

 branch, and commencing as two narrow, widely separated bands even from the chin, furnish a 

 good family character, as does also the large, elongated, elliptical or lanceolate ephippial space, 

 which reaches to the caudal pit (Cypselus), or even to the oil-gland (TrocJnJi's). By both these 

 characters they are definitely distinguished from the Passerinse, whilst they, to a certain extent, 

 approach the Caprimulffida?, especially the genus Nyctornis, in which, however, the inferior tract 

 has an interior gular branch, and the spinal tract is at once weakened and dilated in its posterior 

 part, characters which do not occur in the Macrochires. Both genera of this family have, 

 moreover, ten rectrices, and usually only sixteen remiges, of which ten are seated on the hand. 

 The latter are characterised by their enormous length, their very strong shafts, and their very 

 narrow, but thick outer vane. The first is almost always of equal length with the second, and 

 these are the longest ; very rarely I have found the first shorter than the second. The naked oil- 

 gland has no circlet of feathers at the apex. 



1. Cypselus. The presence of down-feathers on the spaces, the very large aftershaft on 

 the contour-feathers, and the narrow form of the bands of the spinal tract, constitute the characters 

 of this group. 



a. In Hemiprocne NOB., to which Acanthylis or Chcetura may also be referred, I find 

 remarkably long, strong, and densely feathered lumbar tracts, and the spinal tract diminished iu 

 its posterior portion from the shoulder-blades. In H. collaris (TfiMM., PL Col., 195 ; Cypselus 

 torquatm, LIGHT.) the stems of this tract are rather broad, and contain several rows of feathers ; 

 in H. ncuta (Cypseltts acutirs PR. MAX. v. NEU WIED, 'Beitr.' iii, 1, 351) the anterior part 

 consists of two rows of feathers, and is apparently interrupted at the nape, whilst the hinder part 

 is uniserial on each side, and divided as far as the oil-gland. The latter is very small. The stiff 

 tail-feathers in both species terminate in horny, acute points. In the second I found sixteen, 

 remiges. 



b. The true Cypseli, of which I have carefully examined only C. apus (Plate III, figs. 16 and 

 17), have a naked annular spot around both the eye and the orifice of the ear; a uniform, strong 

 spinal tract, three feathers in breadth in each branch near the space, and weaker, although very 



