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PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 39. 



space between the scales and shelf of this thelycum. The sperm 

 consists of innumerable minute spheroidal cells, each showing a large 

 refractive body. 



The important fact is thus established that a large mass of sperma- 

 tozoa is contained within the thelycum much as sperm is contained 

 in the annulus ventralis of Camharus. How this is introduced is at 

 present conjectural, though the anatomy of the petasma of the male 

 leaves little doubt that this compound organ transfers the sperm. 

 The way the secreted mass fills the cavity of the thelycum indicates 

 that it is run in when soft and subsequently "sets" more or less. 

 The place of entry is doubtless the posterior part of the slit between 

 the scales, for series of cross sections show that here the secreted 

 mass comes to the surface as a fine narrow edge. In life there may 

 have been a continuation of the spermatophoral mass through this 

 cleft into the outside water, which might represent the mass described 

 by Spence Bate in other species. 



Fig. 5.— Longitudinal section of thelycum of a mature Peneus brasiliensis, showing the 

 darkly stained sperm enveloped in a light secreted mass and enclosed by the scales 

 (sc) overlapping the shelf (s). 



But this raises the question, how far are these sperm-containing 

 secreted masses within the thelycum to be regarded as spermato- 

 phores ? 



If a spermatophore is a bag or receptacle of secreted matter 

 that is fashioned by the male and then transferred with little change 

 to the female, the mass that fills the thelycum in P. hrasiliensis 

 can scarcely be regarded as a true spermatophore, though it is 

 doubtless of the same essential nature. As the mass is some 4 mm. 

 wide, 6 mm. long, and 3 mm. deep in a female 110 mm. long, and 

 as it fills all the cavity of the thelycum as if run in when essentially 

 flowing or liquid, it would appear more like a secretion of the male 

 deferent duct conducted by the petasma than a true preformed 

 spermatophore formed and to some extent made firm within the 

 male duct and then merely manipulated by the petasma. Better 



