298 J. H. ASHWORTH. 



They have a spacious coelom, subdivided anteriorly by dia- 

 phragmSj and non-septate in the middle part of the animal; 

 the alimentary canal consists of an eversible pharynXj fol- 

 lowed by an oesophagus bearing a pair of lateral glandular 

 outgrowths, a dilated stomach with glandular walls, and a 

 straight intestine, usually with a ventral groove ; the blood- 

 vessels of the middle region of these animals are so arranged 

 as to leave the stomach considerable freedom of movement, 

 all the blood-vessels to the stomach passing to its ventral 

 wall, and being arranged so that they can accommodate them- 

 selves to the backward and forward motion of this part of the 

 gut. 



The Scalibregmidse agree with the Arenicolidge in the 

 above-named characters, and in the general shape of the 

 body, the subdivision of the segments into annuli, the sculp- 

 turing of the skin, the small-lobed prostomium (which, in 

 some specimens of Scalibregma, is quite comparable to 

 that of Arenicola claparedii), and the presence (in Scali- 

 bregma and Eumenia) of gills of a similar type. The 

 brain and non-ganglionated nerve-chain of Scalibregma 

 resemble those of the marina section of the genus Areni- 

 cola. There are also points of difference between these two 

 families which are of considerable importance. In the 

 Scalibregmidee the two rami of the parapodia are practically 

 identical, but in the Arenicolidge the notopodium is a 

 conical elevation, and the neuropodium a cushion-like out- 

 growth. In members of the latter family the neuropodium 

 bears crotchets only, and the notopodium bears capillary 

 setse ; in the Scalibregmidse both rami of the parapodia bear 

 two kinds of setge, capillary and furcate, the latter being 

 characteristic of the family. In some of the Scalibregmida) 

 the parapodia form laminate appendages bearing dorsal and 

 ventral cirri, which are absent in Arenicola (cirri are very 

 rarely seen in the posterior region of American specimens of 

 A. cristata). The gills of Scalibregma and Eumenia 

 are confined to the first five (or six) segments; they are 

 never present in the first seven segments of Arenicola, 



