576 GEOLOGICAL SURVEY OF THE TERRITORIES. 
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EXPLANATION OF PLATE XXXI. 
1. Apus lucasanus Pack. Seenfrombeneath. Enlarged 34times. md, mandibles. 
2. Apus lucasanus Pack. First antenne. 
2a. Apus lucasanus Pack. End of the same magnified. The antennes of both 
pairs drawn to the same scale. 
3. Apus lucasanus Pack. Maxilla, showing the (a) anterior and (0) posterior di- 
visions of the free edge; maz, the gill of the maxillipede. 
3a. Apus lucasanus Pack. Maxillipede, represented by the gill only. 
4. Apus lucasanus Pack. First leg giving (with some changes) Lankester’s nomen- 
clature of the parts; ax!-axi, the pseudojoints; en!—en®, the six endites, with 
the gill and flabellum. 
5. Apus lucasanus. The oostegite, or part of the 11th pair of legs of the female 
containing the eggs; os, aperture of the sack; fl, modified flabellum; x, the 
greatly enlarged subapical lobe (compare Plate XVIII, figs. 2, 3, 4a, and. 
Plate XXXII, fig. 2x); br, the gill. 
6. Limnetis brachyura (Europe). Ant!, 1st antenne; ant?, 2d antennw; lab, 
labrum; sh. g, shell gland; int, intestine; ht, heart; add. ms, adductor mus- 
cle; oc, ocellus; md, mandible; liv, liver. 
. 7. Limnetis brachyura, Section through the body and shell (sh); ht, heart; int, 
intestine; ov, evary; 1-6, the six endites. 
. 8, Limmnetis brach, yura. Brain (br) and nervous cord; n. ant', origin of 1st anten- 
nal nerve; n. ant?, 2d antennal nerve; md. g, mandibular ganglion ; mz. g, 
maxillary ganglion; GaGes succeeding thoracic ganglia. Other letters as 
in Fig. 7. 
9, Distomum apodis Pack. Amer. Naturalist, vol. xvi, p. 142, Feb., 1882. Side 
view, greatly enlarged. A parasite in oostegite of Apus ‘Iucasanus.. 
9 bis. The same; ventral view. 
ig. 1 drawn from nature by J. 8. Kingsley; Figs. 6-8 copied from Grube; the others 
drawn with the eamera by the author. 
