42 ; ACARIDEA. 
The female differs from the male by its larger size and the more oblong ‘shape of the 
body, the abdomen being cylindrical from the hind legs, and by the want of the anal 
appendices. The abdomen is simply rounded at the apex, the hind margin bearing a 
small round excision in its middle. The legs, the dorsal hairs and lateral spines, the 
epimera, the palpi, and mandibles are as in the male. A chitinized stripe of brownish 
colour and semicircular shape is situated transversely before the genital orifice. 
This species lives gregariously in the wing-feathers of the ‘* Pajaro bobo” (Momotus 
lessont). In running, the female takes the lead and draws the smaller male after her. 
In the act of copulation the female places her abdomen above the anal appendices of 
the male. (In figg. 1, 2 this connection already appears loosened a little.) I 
observed this species in November 1880. 
P. momotorum bears, by the form of its anal appendices, a remarkable affinity to 
P. phylloproctus, Trouess. et Mégn., which inhabits the Haliéetus leucogaster of the 
Indian and Chinese seas. It seems to be even more closely allied to this species than 
to P. biemarginatus and P. ramphastinus, Trouess. et Mégn., which are parasites of 
various South-American birds. 
PROCTOPHYLLODES. 
Proctophyliodes, Robin et Mégnin, Mém. sur les Sarcoptides plumicoles, p. 629 (1877). 
1. Proctophyllodes sialiarum, sp.n. (Tab. XXI. figg. 3,¢; 4, 4a-¢, 2.) 
3. Corpus minimum, albidum, translucidum, circiter quarta parte minus quam in femina, sat longum, paul- 
lulum angustius quam in femina, pedes anteriores atque posteriores interstitio longo segregati. Omnes 
pedes inter sese fere sequales, breves, Maxima latitudo corporis ante coxas tertii paris. Ante eas spina 
recta prope marginem inferne sita est. Post pedes tertii paris corpus crassitudine diminuit. Appendices 
anales sat breves, carnose, conics, separate incisura profunda, in quavis appendice 3 sete diverse longi- 
tudinis adsunt. Disci adhesivi in appendicum basi prope marginem internum inferne siti. Mandibule 
breves, chelarum brachia longa, angusta, et ita curva ut clausa apicibus solum sese attingant. 
Long. circiter 0°25-0°5 millim. 
2 adulta. Corpus majus quam in mare. In abdominis apice furca carnosa adest, que inferne prope marginem 
convexum externum in utroque latere spinam lanceolatam sat longam fert. Furce apex cujusque lateris 
in appendicem longam, sinuatam acutissimam desinit. Epimera primi paris utriusque lateris in media 
regioni sternali sese conjungunt, secundi paris angulariter retrorsum fracta late discreta remanent. In 
corporis latere, paullulum post medium interstitii inter pedes secundi et tertii paris seta sat longa inserta 
est. Inventre medio trabecula transversa arcuata seu semicircularis adest, que in utroque latere brachio 
longo annulum coxe tertie attingit. Mandibule ut in mari. 
Long. circiter 0°5 millim. 
2 nympha. Abdomen in appendicem conicam, carnosam, incisura bipartitam desinit, que in superficie externa 
utriusque lateris spinam lanceolatam sat longam et in apice setam longam gerit. 
Larva hexapoda minima, jam rudimenta appendicum analium adulte preebet. 
Ovum longum, fusiforme, translucidum, sat magnum, ad cribri instar perforatum. 
Hab. Guatemata, Retalhuleu (Stol/), in remigibus Sialia sialis gregatim. 
Male very small, long and narrow, of a whitish, somewhat transparent colour, about 
one-fourth smaller than the female. The two anterior pairs of legs are separated by a 
