326 GEOLOGICAL SURVEY OF THE TERRITORIES. 
We should regard A. longicaudatus as standing at the head of the 
genus, and the Kuropean species, A. cancriformis, lowest, the former 
species being on the whole more specialized, since the carapace is in A. 
longicaudatus smaller, not reaching to the. middle of the whole body, 
while that of A. cancriformis is more as in the larval stages, since it 
reaches nearly to the telson, nearly concealing from above the limbs. 
The frontal doublure is also much smaller than in the European species, 
while in the latter species the caudal appendages are considerably longer 
than the body, in A. longicaudatus being barely one-half as long as the 
whole body. On the whole, therefore, A. longicaudatus seems nearer 
allied to Branchipodide, while A. cancriformis, by its large shield cover- 
g meatly the whole body, shows some slight approximation to the Limna- 
tad. 
APUS DOMINGENSIS Baird. 
“Apus Domingensis Baird, Proc. Zool. Soc. London, Part xx, 5 (Tab. 22, fig. 1), 1852. 
““Clypeo corporis dimidiam partem tegente, 
rotundo, tenui, corneo; ramo externo pedum 
primi pariscorpus equante. Long. toti corporis 
1 poll; lat. clypei 2 poll. 
“« Hab.—In Insula St. Domingo, India Occi- 
dentali. Collegit M. Sallé. Museum Britanni- 
cum. 
“Though a native of the West Indies, this 
species may be easily distinguished from A. 
Guildingit by its round-shaped carapace of a 
horny colour, covering half the body of the ani- 
mal, and its external branch of the first pair of 
feet only the length of the body, while in A. 
Guildingit it exceeds the whole body and caudal 
filament included. The carina down the center 
of the carapace, and the fork which it takes at 
the anterior extremity where the division into 
cephalic and thoracic portions takes place, are 
marked throughout their length with a deep 
brown color, as are also the short stout spines 
on the abdominal portion of the body. These 
are straight, not hooked, as in some of the otfer 
species. The caudal filaments are nearly the 
length of the body, and are covered with very 
numerous, extremely short sete. The ovipar- 
ous feet are present in all the specimens I have 
examined, but none contain any ova.” 
This species (Fig. 16) is very closely allied to 
AE ee ale A. equalis, and represents that species in the 
larsed. After Baird, «West Indian fauna. 
APUS GUILDINGII Thompson. 
Apus Guildingii Thompson, Zool. Researches, Fasc., v. 108, t. 6, fig. 3; Milne-Ed- 
wards, Hist. Nat. Crust. iii, 561. Baird, Monog. Family Apodidx, Proc. Zool. Soc. 
London, Pt. XX, 3, 1852. Clypeo corporis vix dimidiam partem tegente, quadrato, 
membranaceo, nigrescente ; ramo externo pedum primi paris longissimo, totum cor- 
pus, filamentis caudalibus inclusis, excedente. 
Hab.—In Insula “St. Vincents,” India Occidentali; Rev. Lansdowne 
Guilding. 
