22 



same pair, the food being held between the two. This chewing by means of these 

 opposing rasps reminded me," writes Dr. Lockwood, " of the hand carding-process, in 

 which the card held by the right hand is brought towards and against the one held in 

 the left hand, the wool being between, when the right hand card is held still, and the 

 left hand duplicates the motion, and so on. The fine particles rasped off by the incurved 

 teeth pass into the mouth " *. 



Tlie tumid and wrinkled margins of the mouth quickly contract to an oesophagus about 

 a line in diameter. This tube (PI. II A. fig. 2, ee) curves upward and forward in a 

 course of Ij inch ; then dilates into a conical proventricular cavity (r) extending down- 

 ward, about 5 lines in depth by 3^ in breadth at the base. From the fore part of the 

 base a second short canal ascends, to terminate by a slight vascular prominence in the 

 stomach (s). The epithelium, or modified chitine, continued from the mouth along the 

 gullet and proventriculus, becomes suddenly thickened in the stomach, and is disposed in 

 numerous transverse ridges. The muscular coat of the stomach is concomitantly 

 strengthened, attaining at one part a thickness of 3 lines. The pyloric end {mt) projects 

 as a truncated cone, 4 or 5 lines long, into the dilated beginning of the intestine (i). The 

 truncate apex of the pyloric cone is slightly tumid. The epithelium lining that part has 

 resumed its thinness and subtransparency. 



The intestinal tunics appear to be reflected from the base of the pyloric cone ; they 

 define a dilated beginning of the canal, and gain a slight thickness of the muscular coat 

 as they contract to the common size of the intestinal tube, the area of which is about 

 5 lines in transverse, and 3 lines in vertical diameter. The tube goes nearly straight to 

 the vent (PL II a. fig. 1, i, v) ; but, about halfway there, it contracts transversely (PI. I. 

 fig. 1, i), and exchanges its oval for a cu'cular section, with a diameter of 2^ lines. Near 

 the vent it again expands, chiefly transversely ; and the muscular coat there gains some- 

 what in thickness. The vent (PI. II A. fig. 1, v) is a transverse slit with tumid margins, 

 just anterior to the joint between the thoracetron and pleon. 



The contents of the alimentary canal were pulpy and scanty. The principal food of 

 the Limulus loolypliemiis is stated by Dr. Lockwood {loc. cit.) to be Nereids, routed by 

 the cephaletral limbs out of the mud or sand displaced in the act of burrowing. 



The only gland in communication with this canal is the liver. It is of great size ; its 

 minute terminal acini are compactly massed together, and occupy most of the space in 

 the cephaletron not given to other organs, mainly the generative, the ramifications of 

 which interlace with the hepatic lobes. A part of this mass is shown at n, fig. 1, 

 PI. I. ; but it extends forward to the space anterior to the stomach, and backward by 

 a narrow tract (ib. n') on each side of the intestine in the thoracetron. The lobes, or 

 larger groups of acini, form a close-packed series on each side, corresponding in the main 

 in number with the apodemal spaces and the epimeral nerves. The least unsuccessful 

 trials of injecting the terminal canals and acini indicated the greater transverse and less 

 longitudinal extent of the hepatic lobes or primary divisions of . the gland (as shown 

 at ti", fig. 1, PI. I.). The gathering tubes of the initial or acinal ducts of these lobes 

 course, in the main, transversely toward the intestine until they quit the lobe, when they 



* Lockwood (Eev. S., Ph.D.) in ' The American Naturalist,' vol. iv. p. 260 (1870). 



