66 Charles GELDERD 



FTG. 34 Transverse section through the cardiac chamber The ridge c in this 

 species is cone-shaped and of large dimensions. Above the cavity run the two tubes 

 of the digestive gland gl. 2/3 X 5. 



Siriella. 



FiG. 35 to 40. 



FIG. 35. Vertical section through the médian plane. The sections of a pair 

 of folds fl are seen in the anterior upper portion of the cardiac cavity. They con- 

 stitute maze-like formations and end in a small pouch p. The dorsal diverticulum 

 div. is but slightly developed. The intestinal cuticle has been detached from the 

 epithelium by the action of the fixing solutions. 2/3 in, X i- 



FIG. 36. Transverse section through the front part of the cardiac chamber to 



show the insertion of the folds fl in the floor of the cavit}'. They are seen to 



consist of a double row of cells. Above the cavity are the pair of dorsal tubes of 



the digestive gland gl. which in this species as in AncJiialiis run forward over the 

 stomach cavity. 2/3 in, X i- 



FIG. 37. Transverse section through the cardiac chamber, The pièces 5i hâve 

 a vertical position. The upper corners are fringed with long spines which meet in 

 the centre of the cavity. In bl. a pair of blood lacunes are seen which in this 

 species are found running by the sides of the stomach cavity. 2/3 in, X 3. 



FIG. 38. The same further back. The upper reliefs bear hooks instead of 

 saw-like teeth t. The longitudinal ridge c is of large dimensions with a flattened 

 summit. 2/3 in, X ^• 



FIG. 39. Transverse section near the entrance to the pyloric chamber in the 

 same région as fig. 6. The terminal aspect of the cardiac plates 5; is seen with 

 the teeth t upon their upper borders. The dorsal vessel runs above the pièce /. 5. m. 

 in connection with a pair of blood lacunes, bl. 2/3 in, X 3. 



FIG. 40. Transverse section through the middle of the pyloric chamber. The 

 médian pièce S^ hears a tuft on its summit. It contains three pairs of latéral 

 grooves gy. 2/3 in, X 3. 



Nyctiphanes couchii. 

 Fig. 41 and 42. 



FIG. 41. Vertical section through the médian plane partly diagrammatic, showing 

 the relative positions of the stomach pièces. The cardiac chamber is greatly developed 

 and elongated in the longitudinal direction. The pyloric is comparatively small. 

 This species is distinguished by the length of the latéral pièces 5, and the great 

 development of the longitudinal ridge which terminâtes at the pyloric chamber as 



