16 A. S. PACKARD, JR., ON THE ANATOMY 



unable as yet to find any specimens of the young with the enteric canal in such an early 

 stage of development as to throw any light on the morphology of the stomach.^ 



Structure of the liver. The tubules of the liver spread everywhere through the 

 cephalothorax, reaching almost to the edge of the retina of the eyes, and when cut 

 through, show in sections, as at plate 3, figs. 9, 9a, 96, a circular or oval layer of epithelium, 

 surrounding a cavity more or less irregular in size and form. The cells are quite large 

 and filled with brownish granules, being dark at base and transparent towards the end 

 where they project into the cavity. 



Plate 3, fig. 8, represents the end of a lobule from theliving horse-shoe crab. Com- 

 pared with that of the lobster (plate 3, fig. 10), they are from one half to a third smaller, 

 very much longer, more intestiniform, and contracted irregularly, while the pigment 

 granules are thicker, and the entire mass is blackish-brown. Figs. 8a, 86, 8c, represent 

 the cells comprising the epithelium teased out and spherical in form. Fig. 8a, indicates 

 a cell containing smaller nucleated cells of two kinds, the smaller clear and yellow, the 

 larger, darker and horn-colored ; 86, a clear, nucleated cell ; 8c, represents dark, clear 

 amber-colored cells filled with the secretion, and with the nucleus no darker than 

 the rest of the cell, and very clear. For purposes of comparison we give figures 

 (plate 3, fig. 10) of the end of a liver-lobule of the lobster, which is pale green, with 

 numerous epithelial cells, a few oil globules being scattered through them. In the living 

 lobules of a species of Panopaeus common in Buzzard's Bay, some of the cells are 

 colored yellowish-green, imparting the same color to the entire lobule ; the cells in Pan- 

 opaeus (plate 3, fig. %d) are clear of granules, almost as much so as the fat globules. The 

 lobules of the liver of this crab are larger, more conical and shorter than in the lobster. 

 From this it will be seen that fundamentally both the general and minute structure of 

 the liver of the Decapoda and Limulus is nearly identical. 



The glandular bodies supposed to be renal in their nature. These glands had 

 remained undescribed, until in a paper read at the Philadelphia meeting of the National 

 Academy of Sciences, held in November, 1874,^ we drew attention to their occurrence 

 and histological structure. Although we have nothing to add verbally to the account 

 then given of the gross anatomy of these glands, we would refer to the figure (plate 3, 

 fig. 7) illustrating the form, and the cells (plate 3, figs, la, 76, 7c) composing these glands. 

 They do not appear to have been described by Van der Hoeven, Owen, or A. Milne- 

 Edwards, in their account of dissections of this animal. 



These glands are quite large, and apparently of some physiological importance, 

 and are easily found, as they are conspicuous from their bright red color, causing 

 them to contrast decidedly with the dark masses of the liver, and the yellowish 

 ovary or greenish testes, near which they are situated. The glands are bilaterally 

 symmetrical, one situated on each side of the proventricle and stomach, and each is 

 entirely separate from its fellow. Each gland (plate 3, fig. 7) consists of a stolon- 



1 I have found in the crop (stomach) of a large Limulus In another, occurred an Edvvardsia, still alive, and three 

 several living spiny larvae of Homalomyia, and several dead or four large Nereis virens. 

 ToUennia gemma, mixed with bits of seaweed and Zostera. ^ American Naturalist, ix, 511. September, 1875. 



