108 E. A. Andreios — Anatomy of the Sjyider Crab. 



ossicles) are the only ones visible on the dorsal surface of the 

 cardiac region. 



On the ventral surface a single median cartilaginous plate forms 

 the posterior face of the cardiac region and projects as a tongue- 

 shaped process into the mouth of the pylorus. This is the posterior 

 cardiac ossicle, and leads from near the oesophagus to the opening 

 into the pylorus where it is fringed with setae. Between its forked 

 lower extremity and the opening of the oesophagus a median lamella 

 projects into the cardiac cavity. The posterior cardiac ossicle is 

 closely united on each side to a slender ossicle (wp, fig. 17), which 

 forms a rim along the lower posterior edge of the cardiac region. 

 Each of the slender ossicles articulates at its upper posterior end 

 with a slender vertical ossicle {2^1, fig. 17), the postero-lateral, which 

 joins above to the supero-lateral ; and it is also joined to the lower 

 anterior ossicle {ij)", fig. 1 7) of the pylorus. Just above and parallel 

 to each of these rim-like ossicles («;;, fig. 17) a more slender ossicle 

 {il), the infero-lateral, supports a delicate fringe of setai lying 

 parallel to the posterior cardiac plate and to a sipiilar fringe arising 

 just above the infero-lateral ossicle. The ciu'ved lower end of this 

 ossicle («, fig. 17) is attached to a papilliform process, covered 

 with long setfe, which stands at the lower end of the double fringe. 

 Its curved upper end (Z>) articulates to the lateral cardiac piece {be). 

 This is a small infolding of the cuticle projecting into the cardiac 

 cavity as a five-clawed, calcified process, below the large toothed 

 surface of the supero-lateral ossicle. It is joined to the latter ossicle 

 by a long curved ossicle {ac), the accessory cardiac ossicle, which 

 passes forward and upward and is connected by a short cartilaginous 

 piece [Tc) with a projection on the slender anterior part of the supero- 

 lateral ossicle. 



There are thus twenty distinct ossicles visible on the external sur- 

 face of the chitinous lining of the cardiac portion of the stomach, four 

 median and sixteen in pairs. There are also two slightly calcified 

 areas on either side above the ceso])hagus (>/?, ri, fig. 17) which inter- 

 nally are covered with scta^ Moreover, behind each supero-lateral 

 and each lateral toothed process, and on each side of the jjra^pyloric 

 ossicle, behind the urocardiac, a cushion-like process set with numer- 

 ous seta^ projects into the cavity of the stomach. 



The chitinous cuticle of the pyloric region of the stomach is much 

 compressed along its lower half; but its lower edge projects outward 

 as a broad shelf, formed posteriorly by the well calcified lateral 

 pouch (t>, fig. 17) on either side. TJ»e upj)er more, cylindrical portion 



