LIMIFOSSOR TALPOIDEUS. 69 



connective-tissue fibres, and is surrounded by a pericardial cavity that posteri- 

 orly extends as a slit-like space between the cloacal and body walls far along 

 toward the posterior end of the body. 



In its general features the nervous sj^stem closely resembles that of C 

 erudita and C. attcnuata. The labio-buccal system has been worked out in detail, 

 but it is no exception to the statement just made. 



The gonad is of large size and is distended with spermatozoa that have made 

 their way through wide canals into the pericardium. As usual the pericardial 

 openings are situated close to the suprarectal commissure, and lead into clearly 

 defined ciliated ducts which very soon unite with the glandular portion. In this 

 species the glandular portion is at first relatively slender, and but little convoluted 

 yet it soon enlarges greatly, becomes much folded and extends as may be seen 

 in Plate 30, figs. 5, 7, from the posterior limit of the gonad to its opening into 

 the cloacal cavity. 



Limifossor talpoideus Heath. 



Zool. Anz., 1904, 5, p. 2S. Zool. Jahrb. Abth. Anat. Ontog., 1905, 5, p. 21. 



Several specimens of this species were taken in Alaska in the Lynn Canal 

 (Sta. 4258) and in Chatham Strait (Sta. 4264) at depths ranging from 282-313 

 fathoms. The general appearance of these animals is shown (Plate 10, fig. 1). 

 The length ranges from 6-12 mm. and the diameter from 1-2 mm., the ratio 

 1 : 6 being constant. 



The mouth, almost terminal in position, is bounded by the sensory plates 

 (Mundschild) and more dorsally by the type of spine covering the prothorax 

 generally. The plates in life undergo rapid changes in form, but histologically 

 and in their innervation they resemble their homologue in Chaetoderma. The 

 deep semicircular groove (halbmondformige Grube) situated beneath the mouth 

 and sensory plates, is lined throughout with the spiculose integument of the bod}'. 

 The spines are triangular or leaf-like and range in length from 0.02 mm. in the 

 region of the mouth to those about the cloacal chamber 0.38 mm. long. 



The hypodermis is relatively very thin, the boundaries of the cells indis- 

 tinct and similar in general to that of other species of Chaetoderma. The 

 somatic musculature likewise is very similar in the two genera. 



The mouth leads into a comparatively narrow canal with longitudinal folds 

 covered with a well-defined cuticle. In the region of the radula the canal enlarges, 

 develops a subradular pocket (Plate 10, fig. 4) and dorsallj^ continues as a cir- 

 cular tube to its junction with the stomach. Attached to a dorsal diverticulum 

 numerous cells pour their secretion into the pharynx. A clearly defined subradu- 



