398 GEOLOGICAL SURVEY OF THE TEEEITORIES. 



more enlarged view of one of the lobules, there being a single layer of 

 secreting nucleated cells. 



The relations and cellular structure of the oesophagus of the same 

 species are seen in figs. 1,4, oes, and 4«. A section of the oesophagus 

 where the microtome passes through the brain and larv^al ocellus shows 

 that the walls of the oesophagus are formed above of two layers of epithe- 

 lium and beneath of three or four, the serial arrangement of the ceils 

 below not being so marked as above. 



In Fig. 1 we see that the razor passed through the oesophagus 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 Apodidw, as seen in Plate XXXII, figs. 1 and 2, the mouth is 

 situated between the mandibles. The oesophagus 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. tl int. The intestine gradually con- 

 tracts towards the narrow rectum, the anus (an) being snmll and situated 

 rather dorsally than ventrally, as in most, if not all, Anthropoda, and 

 opening between the bases of the cercopods. 



In living examples of Artemia gracilis (Plate XXIII, figs. 1, 2), the 

 oesophagus is very short, while the stomach is situated in the head. 

 The stomach is apparently divided by a medio-longitudinal constriction 

 into two large sacks or pouches, these being the ducts to the liver, which 

 has a few short lobules, the liver being much less voluminous in the 

 BrancMpodidce 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 (bisenosome), and 

 the other in the urosorae. 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 int). It contracts at the base of the 

 urosome and forms a slender tube one-half the diameter of the anterior 

 portion (fig. 3, int), 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 XXXT, fig. 7 ( Limnetis alter Grube) ; tliose of 

 EstJieria mexicana in Plate XXXIII, figs. 1 and 6. The ovary in Lim- 

 nadiadcB forms a rather large mass, situated in the body behind the head , 

 Fig. G, Plate XXXIII, represents a portion of the ovary of Esther ia mex- 

 icana., 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 appearance 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 Branchipodidce 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, 26, 3,4,4fl, 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 



