320 PE.or. d'arct w. Thompson on the [^pi'- 2, 



in the main the two tracts are separated by a prolongation back- 

 ward of the triangular apterion at the base of the neck. 



The poUex is entirely concealed beneath the skin and bears no 

 free alula, though a few somewhat larger feathers appearing 

 among the marginals correspond to the position of the latter. 



The whole wing is of a remarkably simple type. The small 

 number of marginals, the scanty feathering of the patagium, and 

 the absence of minor coverts on the whole dorsal and greater part of 

 the ventral surface of the wing seem to me to leave the ari-angement 

 of the remaining rows unusually clear ; and in particular, the 

 relation of the upper and lower posterior extensions, parapteral 

 and hypopteral, of the coverts to the rows of coverts themselves 

 seems to be much more simple and definite than is usual. 



The wing of Collocalia has ten primary feathers and seven well- 

 developed secondaries, internal to which latter are two rudimentary 

 ones. There is a greater covert to each of the primaries on the 

 dorsal side and another on the ventral, of which, if my inter- 

 pretation be correct (for it is in part subject to the same difficulty 

 that I have discussed in describing Fatagona), the ventrals are all 

 proximal to, and the dorsals distal to, their corresponding primaries. 

 There seem here to be clearly intercalated at the wrist a pair of 

 dorsal and ventral carpal coverts. There is no aquincubital covert 

 among the secondaries, at least in this particular Swift ; there are 

 seven major coverts on the ventral side, and on the dorsal side the 

 series is further prolonged backwards to connect with the humeral 

 tract. On the dorsal side of the wing there are median coverts 

 present in connection with the seven outer primaries and all the 

 secondaries, which latter are furnished also with a row of minor 

 coverts. Median coverts are present on the ventral side in 

 connection with all the primaries and secondaries, and are further 

 continued backwards into a line of hypopteral feathers. On the 

 ventral side of the manus is an incomplete row of minor coverts. 

 The marginals are few, but the patagium bears on the dorsal 

 surface more numerous feathers (in 3 or 4 rows) than in the 

 Humming-bird. 



The wing of Caprimulgus macrurus (text-fig. 82, p. 321) possesses 

 ten primaries and ten conspicuous, together with one or two rudi- 

 mentary, secondaries. There is a rudimentary remex at the carpal 

 joint. The alula is of large size and bears three long feathers. 

 On the dorsal side of the wing there is a major covert corresponding 

 to each primary, to each secondary including the rudimentary 

 carpal remex, and also a well-marked ' aquintocubital ' feather. The 

 six outer primaries (that is to say, numbers 5 to 10) possess each 

 a well-formed median covert, and the first and second also each 

 possess two coverts, the outer (or that corresponding to the median 

 covert) being of large size, though not so big as the major one ; 

 besides these, the dorsal surface of the hand possesses no other 

 coverts. 



The secondaries all possess well-formed median as well as major 

 coverts, including one for the aquintocubital feather ; and these are 

 succeeded by three rows of minor coverts, which rows become 



