78 



DR. C N. ANNANDALB 



-xio. 



Fig. 2, 

 Scalpellum sociabile, 

 mandible. 



Appendages, etc. — 



■First Cirrus not very widely separated from second ; the two rami not highly 

 differentiated, both gradually diminishing towards tip and provided 

 with a terminal bunch of hairs, neither deeply lobed at the edge, both 

 flattened dorso-ventrally ; anterior ramus slightly broader than posterior ; 

 posterior fitting into naked concave posterior half of anterior ; the re- 

 mainder of the ventral surface of 

 both covered with short, silky hairs. 

 Anal Appendages short, consisting of 

 a broad, antero-posteriorly flattened 

 proximal joint and four minute, more 



or less cylindrical distal joints ; the outer margin of the 



former almost straight but with an excavation near 



the base, the margin directed towards the anus strong- 

 ly convex, meeting the margin of its neighbour in the 



middle line ; this joint longer than the sum of the 



others ; the terminal joint not reaching the middle 



of the second joint of the sixth cirrus. Penis stout 



and long, covered with minute hairs, not distinctly 



annulated. 



Fig. 3-— x 3°' 

 Scalptllum sociabile, anal appendages 

 from behind. 



Mouth- Parts— 



Labrum rather small, not very prominent. Mandibles with three teeth, the inner- 

 most long and simple, very blunt, the second and third widely separated, small. Maxilla 

 with free surface concave towards inner bristle, slightly convex towards other extremity ; 

 bristles not highly differentiated. 



Observations — 



There are traces of pigment in this species in the form of minute, star-shaped cells 

 on the surface of the mouth-parts and of blotches on the proximal joints of the cirri 

 and a suffusion on the anal appendages. The pigment is of a purplish colour. The anal 

 appendages are noteworthy. The mouth-parts are feebly developed. 



I do not know of any other Scalpellum which is quite so gregarious as this species. 

 In some other forms, e.g., 5. squamulifentm (which is by far the most abundant in the deeper 

 parts of the Bay of Bengal), numerous individual may be found attached to the same object 

 {e.g., to the glassy filaments of a Hyaloimna or, more rarely, the shell of a Xenophora) and 

 occasionally one individual grows up on the peduncle or capitulum of another ; but the 

 practice is not carried to the extent of young individuals using, generation after genera- 

 tion, their parents as a support. These instances add point to Hoek's suggestion as to 

 the origin of dwarf or complemental males in the genera Scalpellum and Ibla : — 



" In some of these species specimens attached themselves to each other as well as to 

 other objects, and they developed all into ordinary hermaphrodite specimens. In one of 

 these species, however, young specimens attached to full-grown older ones, though 



