CHAETODERMA CALIFORNICA. 65 



of the protrusible portion of the prothorax is yellowish brown, while the remainder 

 of the body is yellowish green. A rusty red substance, possibly excreta, incrusts 

 the spines in the cloacal region. 



The cuticle is of moderate thickness and rests upon a hypodcrmal layer 

 whose nuclei, placed at various levels in the region of the prothorax, have at first 

 sight the appearance of being more than one cell thick. The most common 

 type of cell is relatively slender and contains an oval granular nucleus. Among 

 these are other elements, probably spicule matrix cells, each of, which contains 

 a spherical nucleus larger in size than those of the foregoing class of cells and 

 placed in the neighborhood of the base of a spine above the general level of the 

 hypodermis. As in C. attcnuala spaces exist at frequent intervals in the hypo- 

 dermis and from the vicinity of each fibres pass into the underlying muscular 

 layer. As noted on page 55 there are reasons for the belief that these are gland 

 cells, of unknown function, whose secretion is dissolved through the agency 

 of alcohol when used as a fixing agent. The shape of the spines is shown (Plate 37, 

 fig. 14). 



The alimentarj^ canal opens through the dorsal half of the buccal plate; 

 its first section (Plate 27) is a narrow canal that rapidly widens in the neighbor- 

 hood of the brain. To its lining epithelium the usual muscles attach and afford 

 lodgment for numerous buccal glands. These last named organs extend from 

 the mouth to the level of the brain and are similar to those of C. nitidulum save 

 that the cells are less compact and of larger size. In the neighborhood of the 

 radula the walls of the pharynx become more folded than in C. nitidulum and 

 are unique in possessing a pouch (Plate 31, fig. 8) of considerable extent, into 

 which the glands of the dorsal side open. Behind the radula the canal gradually 

 narrows, its folds become smoothed out whereupon it unites with the stomach. 



The salivary glands consist of several globular cells surrounding a small 

 lumen that in some instances is in direct communication with the digestive 

 tract. However each cell communicates with a small ductule which gives evi- 

 dence, not of passing the secretion into the lumen of the gland, but directly into 

 the digestive tract through intercellular channels of the lining epithelium. 



The radula presents no especially noteworthy features. Its conical tooth 

 is slightly more slender than is usual (Plate 31, fig. 1), but the cuticular wing- 

 like supports and musculature are entirely tj^pical. 



As usual the pharynx opens by a comparatively narrow pore (Plate 31, fig. 2) 

 into the stomach whose relations to the liver and intestine are normal. Large 

 quantities of organic remains occur in the gut, Radiolaria, diatoms, and sponge 



