232 PROCEEDIJ^GS OF THE NATIONAL MUSEUM vol.88 



Genus SCALPELLUM Leach 



SCALPELLUM COLUMBIANUM Pilsbry 



Figure 5 



Scalpellum (Areoscalpellum) columbianum Pilsbky, 1900, p. 367 ; Cornwall, 

 1930, pp. 215-217. 



This species was described by Pilsbry from three specimens from 

 British Columbia, Cornwall (1930) described the mouth parts of 

 two specimens also from British Columbia and pointed out several 

 variations from the type material, i, e., the greater width of the 

 inframedian latus, the presence of hair on the outer margin of the 

 carina, and the slightly greater width of the capitulum. Cornwall 

 also figures three small individuals found with the two adults. 



Five adult specimens of this species, found off Allen Bank, Puget 

 Sound, were unfortunately preserved dry. One adult and two im- 

 mature forms were found off Point No Point, Puget Sound. The 

 adults resembled those figured by Cornwall more nearly than the 

 type material. In all, the inframedian latus is wider than that of 

 the type and the capitulum is only 1.8 times as long as wide instead 

 of more than twice as long as in the type. 



Other plates show some variation in proportion. In most the 

 rostral latus was more nearly the same width throughout instead of 

 much wider near the inframedian latus. Also the upper latus was 

 in most specimens wider in proportion to the length than in the type. 



The capitulum is covered with a thin membrane on which fine 

 spines occur. These are slightly longer and more numerous near the 

 carina and are especially long along the ridges of the carina. In all 

 the specimens the scales on the peduncle are more numerous, 25 to 

 30 in a row, instead of about 10 as in the type. 



The younger of the two immature forms (fig. 5, a) was very 

 similar to the immature form of S. gi'uvelianum figured by Broch 

 (1922). All the plates except the rostral latus and rostrum were 

 present. The surface was covered with a membrane with fine hairs 

 and a pair of "tentacular appendages" covered with fine hairs oc- 

 curred at the apex of the capitulum. At the base of the capitulum 

 there were two large scales on each side and one smaller scale below 

 the rostral angles of the scuta. In the older specimen the rostral 

 latus was present, and a sixth scale occurred on the peduncle below 

 the carina. In neither individual could the rostrum be distinguished. 



The mouth parts of the specimen examined differed somewhat from 

 Cornwall's description. The upper part of the labrum is bullate 

 (fig. 5, 6) , and the palpi are somewhat acuminated. The fourth tooth 

 of the mandible is less blunt, and a greater part of the surface is 

 covered with hairs (fig. 5, /). The maxilla (fig. 5, d) shows no notch 



