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segments. Several segments have only two pairs of spines at the anterior margin : one pair 

 very long near the extremity and a second shorter pair about the middle of its length. 



Caudal appendages very minute, one-jointed with a few spines near the extremity 

 and a short and feeble claw-like spine at the tip. 



No penis. 



The eggs formed a single cluster in the specimen I opened; they had a much more 

 elongated shape than in several other species of ScalpelliDii. They measured 0,47 X 0,27 mm., 

 their number being 17. 



This specimen was furnished with a dwarf male at one side only. The latter was attached 

 to the inner surface of the scutum near the occludent margin. Its shape was pear-like, the 

 peduncular pole being considerably the narrower. It showed no trace of valves. The prehen.sile 

 antennae were inserted very near the peduncular extremity. Its size was 0,5 X 0,3 mm. 



The "Siboga" collected this interesting little species at: 



Stat. 241. December I, 1S99. Lat. 4° 24'.3 S., Long. I29°49'.3 E. Depth 1570 m. Bottom: dark 

 sand with small stones. 



Observation. This species is very nearly related to Sc. balanoides Hoek collected 

 during the cruise of the "Challenger" at Lat. 5°42'S., and Long. i32°25'E. at a depth of 

 129 fathoms, about 230 m. The latter species has about the same size and lives attached to 

 the arms of JMctacrimis Murray i. Sc. sessile differs from it, i" by the trapezoid not triangular 

 form, of its upper latus; 2" by the greater breadth of its infra-median latus; 3" by the form of 

 its carinal latus, which in .SV. balanoides has the apex, where the umbo is, produced and even 

 slightly recurved; and 4" by the shape of the carina, which is much more strongly bowed in 

 Sc. sessile than it is in Sc. balanoides. Perhaps on closer examination of the "Challenger" form at 

 least some of these differences might turn out to be not so important as I must consider them now. 



18. Scalpclhiiii cilia fiiin n. sp. PI. VII, fig. 17. 



Valves fourteen, covered by membrane, clothed with very long hairs. Carina simply bowed, 

 no flat roof. Tergum very large. Valves of the lower whorl small. Upper latus indistinctly 

 quadrangular. Rostrum small, triangular. 



This very small species is represented by a single specimen only. 



The capitulum elongated, with the apices of the tergum and scutum produced. The 

 hairs which clothe the membrane are longest along the carinal margin of the capitulum. 



The scutum is elongated, quadrilateral, more than twice as long as broad, with the 

 upper part produced and pointed. 



The tergum is large, elongated rhomboid; the umbo is at the ape.x which is bluntly 

 pointed and not produced. 



The uppermost (umbonic) parts of scutum and tergum are naked, not covered by membrane. 



The carina is simply bowed longitudinalh- and also laterally. It reaches to about half 

 the length of the carinal margin of the tergum. 



The upper latus has the scutal margin parallel to the occludent margin of the scutum 

 and its apex is not produced. The carinal and basal margins form together an arch. 



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