398 GEOLOGICAL SURVEY OF THE TERRITORIES. 
more enlarged view of one of the lobules, there being a single layer of 
secreting nucleated cells. 
The relations and cellular structure of the csophagus of the same 
species are seen in figs. 1,4, 0es, and 4a. A section of the wsophagus 
where the microtome passes through the brain and larval ocellus shows 
that the walls of the esophagus are formed above of two layers of epithe- 
lium and beneath of three or four, the serial arrangement of the cells 
below not being so marked as above. 
In Fig. 1 we see that the razor passed through the cesophagus and 
the intestine, the section being oblique, and the digestive canal curv- 
ing considerably in the front part of the body, so that it is cut through 
twice. The comparative size and general relations of the intestine to 
the other viscera are seen in figs. 9 and 10 of Plate XXIV. 
In the Apodide, as seen in Plate XX XII, figs. 1 and 2, the mouth is 
situated between the mandibles. The csophagus is narrow and very 
oblique, while the rest of the digestive canal is large and of quite uni- 
form thickness. The cavity in fig. 1 is the body-cavity, after the digest- 
ive canal has been removed; but that its body-cavity is completely filled 
by the digestive canal is seen in fig. 2 int. The intestine gradually con- 
tracts towards the narrow rectum, the anus (an) being small and situated 
rather dorsally than ventrally, as in most, if not all, Authropoda, and 
opening between the bases of the cercopods. 
In living examples of Artemia gracilis (Plate XXIII, figs. 1, 2), the 
esophagus is very short, while the stomach is situated in the head. 
The stomach is apparently divided by a medio Jongitudinal constriction 
into two large sacks or pouches, these being the ducts to the liver, which 
has afew short lobules, the liver being much less voluminous in the 
Branchipodide than in the two lower families. 
The intestine we regard as that portion lying behind the liver. it is 
divided into two portions, one in the head and thorax (benosome), and 
the other in the urosome. The anterior or cephalothoracic portion is a 
large, straight tube with thin walls, and is of nearly the same thickness 
throughout its length (fig. 2 mt). It contracts at the base of the 
urosome and forms a slender tube one-half the diameter of the anterior 
portion (fig. 3, it), ending in a well marked rectum (rec), which is pro- 
vided with constricting circular muscles, and held in place by three sets 
of slight muscular threads (m). It does not contract at the vent. 
The ovaries.—The relation of the genital glands, particularly the ova- 
ries, are seen in Plate XXXII, fig. 7 (Limnetis atter Grube); those of 
Estheria mexicana in Plate XXXII, figs. 1 and 6. The ovary in Lim- 
nadiade forms a rather large mass, situated i in the body behind the head. 
Fig. 6, Plate X X XIII, represents a portion of the ovary of Estheria mex- 
dcana, showing the epithelial or ovarian cells (ep) and the developing 
egg. It forms a compact mass, situated on each side and below the in- 
testine. The ovary in Apus lucasanus (Plate XXXII, fig. lov and 2 ov) 
forms a loose mass, extending from the region over the mouth to the last 
pair of uropoda. Its general appearanée and histology is well shown in 
the figures of Siebold in his work on parthenogenesis in Arthropoda 
Taf. Il). 
When we ascend to the more specialized Branchipodide we see that 
the genital glands are restricted to a special sac, which grows from the 
under side of the basal uromere. We have nothing new to add to the 
descriptions already given by European authors. Plate XXII, figs. 2, 
2a, 2b, 3,4, 4a, from drawings by Dr. Gissler and myself, give the general 
relations of parts in Artemia gracilis and Branchipus vernalis, and for par- 
ticulars regarding certain points the reader is referred to Dr. Gissler’s 
