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but I observed the testiculum and the receptacuhim seminis in several specimens. The longest 

 diameter of the specimen of fig. 8 measured 0,66 mm., the shortest about 0,5 mm. 



I observed a few (3) males of e.xactly the same shape and structure and at the same 

 place in one of the specimens of the var. gemina from Station 74, and I think the fact that 

 they are wanting in the other specimens must be considered as the consequence of the season 

 or age. While studying the Cirripedia of the "Challenger" more than 20 years ago, I discovered 

 that the larvae of Sc. Strocmi develop into the Cypris-stage before leaving the egg-membrane. 

 Whether all the eggs did so could not be made out; but that there are Scalpelhuns which 

 develop without a free-swimming Naupliusstage cannot, from that di.scovery, be doubted. One 

 might suppose, that only the complemental-males (or the dwarf-males in the unisexual species) 

 had such an abbreviated development. It seems probable, however, that there are several among 

 the deep-sea species whose females as well as males develop without passing through a free- 

 swimming Nauplius-stage. I conclude this from the fact, that I found half a dozen very small 

 specimens (females and males) attached to the surface of the scutum of the large female Scal- 

 pel hint which was collected at Station 5. Darwin speaks of the male larva of Sc. vulgare 

 "crawling on the scuta of the hermaphrodite" and of discovering the fold in the shell where 

 it invariably attached itself: that males should be found on the scutum is not at all surprising, 

 but for the females it would be different, unless it be that they do not swarm out, but creep 

 from the cavity of the mantle in the cypris- or so-called pupa-stage. 



That the little Scalpelhuns I found attached to the outer surface belong really to the 

 same species admits of no question. I figure one of these small animals PI. VI, fig. 11, and 

 the tip of the capitulum more strongly magnified in fig. 12; the capitulum has exactly the same 

 tentacular appendages which I observed in the males and about at the same place with regard 

 to the primordial scutum and tergum. What the physiological meaning of these tentacles is, is 

 difficult to say; they are larval organs which the females seem to loose and which the males 

 keep in mature condition. Morphologically these tentacles are no doubt also of importance — 

 by all means they render us the good service of enabling us to demonstrate that the little 

 females attached to the fullgrown specimens belong to the same species as the dwarf males 

 attached to the mantle-surface between the two scuta. 



C. Sectio: Meso-Scalpellum 

 8. Scalpelhun cJiitinosunt n. sp. PI. VII, fig. 4. 



Valves thirteen, covered by chitinous membrane. .Scutum and tergum imperfectly calcified. 

 Carina with the umbo at some distance from the apex, angularly bent. The part beneath the 

 umbo strongly bent. Upper latus quadrangular, broad with the apex produced in the direction 

 of the scutum. Upper part of the infra-median latus broad triangular. Umbo of the carinal latus 

 at the base, projecting beyond the line of the carina. Rostrum wanting or not calcified. 



The collection made during the cruise of H. M. S. "Siboga" contains two (perhaps 3) 

 specimens of this species. 



The capitulum is flat and very broad, the length being less than one and a half 



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SIBOGA-EXPEDITIE .\XXI(7. '° 



