202 BRITISH FOSSIL CRUSTACEA. 



" ' The food is held immediately under the mouth by the claws or nippers of the anterior 

 pair of jawless feet (antennules), aided if necessary, by some of the others. The basal 

 joints or manducatory haunches then begin an alternating motion of these members upon 

 food by drawing one of the spiny or rasp-like joints against the opposite one of the 

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

 opposing rasps reminded me 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; then 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.' 



" The tumid and wrinkled margins of the mouth quickly contract to an oesophagus 

 about a line in diameter. This tube (PI. XXXIV, fig. 2 ce) curves upward and forward 

 in a course of lj inch, then dilates into a conical proventricular cavity (r) extending 

 downward, 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 moath along the 

 gullet and proventricular, 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 {mi) projects 

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

 The truncated 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 (PI. XXXIV, fig. 1 i, v), but, about halfway there, it contracts transversely, and 

 exchanges its oval for a circular section, with a diameter of 2^ lines. Near the vent it 

 again expands, chiefly transversely, and the muscular coat there gains somewhat in 

 thickness. The vent (PI. XXXIV, 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 polyphemus 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. This mass extends forward to the space anterior 

 to the stomach, and backward by a narrow tract on each side of the intestine in the 

 ' thoracetron.' The lobes, or larger groups of acini, form a close-packed series on each 





