THE ANATOMY OF SCALIBHKGMA INFLATUM. 291 



shape of the prostouiium, the character of the par;ipodia, aud 

 the presence in the former genus of pavapodial and anal 

 cirri. 



Lipohranchius jeffreysii agrees closely with Eu- 

 nienia crassa, except that in the former there are no gills. 

 The absence of gills cannot be ascribed to the youth of the 

 specimens, for three of those in my possession are 32, 38, and 

 40 mm. long respectively, and are almost mature, liaving ova 

 •09 mm. in diameter in the coelomic fluid. These cannot, 

 therefore, be regarded as immature specimens of E. crassa 

 upon which gills would afterwards have been formed, and 

 moreover gills are present in specimens of E. crassa before 

 they reach this size; there are lour pairs of gills in a specimen 

 29 mm. long. Lipobranchius jeffreysii agrees with E, 

 crassa in the shape of its prostomium, and the character of 

 its parapodia, which are without cirri; in fact, given a speci- 

 men from which the first six segments have been removed, it 

 would be a matter of some difiiculty to determine to which 

 genus the specimen in question belonged. 



Among the specimens of Scalibregraa sent to me from 

 the United States National Museum there are five small 

 worms 4'6 to 8 mm. long, which have no gills, but otherwise 

 are indistinguishable from Scalibregma. I find that these 

 are not, as I at first supposed, young specimens ; some at least 

 are almost sexually mature, e. g. the specimen 8 mm. long 

 contains large ova ("1 — 'll mm. in diameter). These, there- 

 fore, cannot well be regarded as young specimens of Scali- 

 bregma; had they been such their gills would ahead}' have 

 been quite obvious structures, for Scalibregma acquires 

 its gills at an early age ; a specimen 5 mm. long already bears 

 the full number (four pairs) of well-developed gills. If, 

 therefore, the branchite are to be regarded as one of the 

 diagnostic characters of the genus Scalibregma, these 

 abranchiate specimens do not belong to the genus. I pro- 

 pose to call them Pseudoscali bregma. 



Several Polychastes have been described which agree with 

 Scalibregma in general characters, but are without gills; 



