194 CHAETODERMA CAITDATUM. 



out. The largest specimen (Plate 9, fig. 1), measures 7.75 mm. in length by 

 1.3 in greatest diameter, while the smallest is 3.3 by .75 mm. In several indi- 

 viduals the anterior end of the prothorax is considerably swollen, giving the 

 entire body a decided trumpet-shape. 



The color, especially of the older individuals, is a slaty gray in the meso- 

 thorax and the posterior part of the prothorax, owing to the dark colored Uver 

 showing through the translucent body wall. The postabdomen is of the usual 

 light yellow tint save the posterior half or third which is very dark brown owing 

 to an incrustation consisting apparently of faecal matter or substances from the 

 coelomoducts. A dark brown or black band encircles the prothorax and this 

 peculiarity together with the shape of the body readily distinguishes the species. 



The dorsal sense organ, in the form of a deep groove, holds the customary 

 position at the posterior end of the body, but owing to the overarching spines 

 it is in large measure invisible in whole specimens. In sections it is seen to be 

 composed of slender cells whose general arrangement and appearance are typical 

 of the genus. 



The mouth opens through the centre of the buccal plate whose general 

 appearance is represented (Plate 9, fig. 4). Between this point and the anterior 

 border of the brain the buccal tube is of moderate size, is folded to form four 

 or five longitudinal ridges, and supports a considerable number of gland cells 

 attached to its outer surface. These last named organs, grouped into lobules 

 (Plate 8, fig. 7), whose general size and shape depend upon the spaces between 

 the longitudinal and radial muscles of the buccal tube, are composed of small 

 cells containing after treatment with Delafield's haematoxylin an abundance 

 of some golden yellow, finely granular secretion. 



The subradular organ is moderately distinct and the tooth (Plate 9, fig. 5) 

 of average size. Behind the radula the canal rapidly narrows, becomes thick 

 walled and the component cells, slender in form, are filled with a dense, finely 

 granular secretion. This condition of affairs continues to the opening borne 

 on the summit of a short papilla (Plate 8, fig. 10) projecting into the gastric 

 cavity. The stomach is a capacious sac, with highly folded walls especially 

 in the neighborhood of the oesophageal opening where the cells are packed with 

 a finely granular, yellowish secretion. In the vicinity of the bile duct the walls 

 are much thinner, nearly smooth and the epitheUal cells are approximately 

 cubical and contain but a small quantity of secretory products. 



The liver presents in general the usual appearance, possessing yellowish 

 brown Kornerzellen and moderately staining Keulenzellen. The intestine, 



