130 



TERRA NOVA" EXPEDITION. 



the free part of the tergum is shorter ; the lower border of the same plate is concave ; 

 the lateral border of the scutum is much less convex ; the inframedian plate is 

 pentagonal, with a thickened triangular area which leaves at the side structures like 

 the radii of a Balanus ; the umbo of the rostro-lateral projects beyond the outline of 

 the capitulum ; the scales of the peduncle are narrower. 



One specimen was taken at Station 349 (off Butter Point, western shore of 

 McMurdo Sound, 80 fathoms), growing on a pycnogonid of the genus Nymphmi. 



Pig. 3. — Scalpellum (Arco- 

 scalpellum) comp actum, 

 n. sp. (?). X 9. i-iti., 

 inframedian plate of 

 opposite side. 



Fig. 4. — Litlwtrya 

 atlantica, n. sp. 

 Capitulum. x 6. 



6 V 



Fig. .5. — Jaws of Lithotrya. a, mandible of L. atlantica ; 

 a', mandible of L. pacifica ; h, maxilla of L. atlantica ; 

 h', maxilla of L. pacifica. 



4. aS. (^4.) compactuvi, n. sp. (?). Fig. 3. 



An Arcoscalpelhmi of about the same size as the supjoosed young stage of S. 

 discovery i (length of capitulum 5 '5 mm.), but differing from it as follows : the lateral 

 border of the scutum is not notched ; the produced angle of the upper lateral plate is 

 much sharper ; the carino-lateral is not notched where it meets the shoulder of the 

 carina ; the umbo of the rostro-lateral projects beyond the outline of the capitulum, 

 but transversely, not with an upward trend, as in S. nymjyhonis ; the inframedian plate 

 is triangular with the apex distal (except on one side of one specimen, where it is very 

 narrow, with a spear-head at the distal end) ; the plates of the peduncle are narrower 

 and more widely separated. 



One specimen was taken at Station 356 (off Granite Harbour, western entrance to 

 McMurdo Sound, 50 fathoms). 



