62 -PHYSIOLOGY OF THE INVERTEBRATA. 



words: "It consists, in the first place, of a transverse, 

 slightly arcuated cardiac plate, calcified posteriorly, which 

 extends across the whole width of the stomach, and articulates 

 at each extremity by an oblique suture with a small curved 

 triangular antero-lateral or pterocardiac ossicle. On each 

 side, a large, elongated postero-lateral or zygocardiac ossicle 

 wider posteriorly than anteriorly, is connected with the lower 

 end of the antero-lateral ossicle, and, passing upwards and 

 backwards, becomes continuous with a transverse arcuated 

 plate, calcified in its anterior moiety, and situated in the roof 

 of the anterior dilatation of the pyloric portion ; this is the 

 pyloric ossicle. These pieces form a sort of six-sided frame, 

 the anterior and lateral angles of which are formed by mov- 

 able joints, while the posterior angles are united by the elastic 

 pyloric plate. 



" From the middle of the cardiac piece a strong calcified 

 urocardiac process extends backwards and downwards, and, 

 immediately under the anterior half of the pyloric ossicle, 

 terminates in a broad, thickened extremity, which presents 

 inferiorly two strong rounded tuberosities, or cardiac teeth. 

 With this process is articulated obliquely upwards and 

 forwards, in the front wall of the anterior dilatation of the 

 pyloric portion, and articulates with the anterior edge of the 

 pyloric ossicle, thus forming a kind of elastic diagonal brace 

 between the urocardiac process, and the pyloric ossicle. The 

 inferior end of this pre-pyloric ossicle is produced downwards 

 into a strong bifid urocardiac tooth. Finally, the inner edges 

 of the postero-lateral ossicles are flanged inwards horizontally, 

 and, becoming greatly thickened and ridged, form the large 

 lateral cardiac teeth. The membrane of the stomach is con- 

 tinued from the edges of the pre-pyloric to those of the 

 postero-lateral ossicle in such a manner as to form a kind of 

 pouch with elastic sides, which act, to a certain extent, ' as a 

 spring, tending to approximate the inferior face of the pre- 

 pyloric ossicle to the superior face of the median process of 

 the cardiac ossicle." 



