108 PROCEEDINGS OF THE ACADEMY OF [April, 



capitulum and peduncle, and have only three valves, the scuta being 

 larger than in Scal'pellum. A subcarina is always present. The 

 inframedian latera have a peculiar square shape, and are quite large. 

 There are 4 pairs of latera in all, therefore 15 valves (a number never 

 reached in Scalpellum, which has no subcarina). The rostrum is very 

 large and prominent. The carina has a submedian umbo in the first 

 two species, apical in the others. Type *S. rostratum Darwin (fig. 1, e, 

 /). Species four or five. 



Dr. Hoek selected no type for his group Euscalpellum, and I have 

 therefore taken his first species as typical. The characters and limits 

 of the group are also much modified, since I place no w^eight upon the 

 shape of the carina, but emphasize the structure of the male, the 

 presence of a subcarina, etc. 



E. rostratum (Darwin). Malay archipelago. 



E. renei (Gruvel). St. Paul de Loanda. 



E. hengalense (Annandale). Bay of Bengal, 98-102 fathoms. 



E. stratum (Aurivillius). Antilles. 



i5J.(?) squamuliferum (Weltner). Indian Ocean, 3200 meters. 



Genus SCALPELLUM Leach. 

 Scalpellum Lead:, Journal de Physique, etc., LXXXV, 1817, p. 68. 

 The males are very degenerate, sack-like, without a peduncle or 

 mouth, the cirri vestigeal, valves absent or extremely small. The 

 female or hermaphrodite has no subcarina (thereby differing from all 

 the preceding genera); upper latera are alwa3^s present, and three 

 pairs of lower latera; rostrum is comparatively small or absent. The 

 position of the umbo of the carina varies from submedian to apical. 

 Plates 14, or when the rostrum is absent 13.^ Type S. scalpellum L. 



(fig.l,^,/^)- 



Scalpellum is morphologically the highest or most modified member 

 of its family, both by the profoundly degenerate males and the advanced 

 type of armor of the hermaphrodites or females. Primarily the genus 

 divides into two subgeneric groups, as follows : 



a. Inframedian latus large, pentagonal (or with the angles rounded), 

 wide throughout, the umbo varying from submedian to basal, 

 or on the rostral border, never apical. Subgenus Scalpellum s. str. 



a'. Inframedian latus generally smaller than the other latera, triangular, 

 hour-glass-shaped or irregular. Subgenus Arcoscalpellum Hoek. 



^ The mere number of plates in the capitulum is not especially significant, since 

 the same number may be present in different genera, but made up of morpho- 

 logically different plates, as in the case of 13-valved species of Scalpellum and 

 Calantica. 



