Introduction to Animal Morphology. 189 



porrig-ens, the lesser Rorqual and Eider duck. E. major, the 

 hedgehog. Paradoxites, found in owls, is divided into 

 metameres, of which the first (proboscis-bearing) and the last 

 three are large. 



Class 5. Gephyrea [Quafrefages). — Dioecious 

 marine, oval, elongate, or sac-like, sometimes ringed, 

 but never jointed, nor with locomotory processes, 

 varying from |" to i' in length. The cuticle is 

 chitinous, sometimes with papillary thickenings, rarely 

 with cnidae(Anoplosomatum Antillense). The dermis 

 consists of connective tissue, containing no spicules, 

 but numerous follicular dermal glands sometimes im- 

 bedded, or on papillary elevations. Some of these 

 are round, each containing four vesicles around a 

 cellular, expanded nerve-ending, sending four bands 

 into the vesicles (organs of Semper). Some have 

 bristles in rows on the surface, and in Bonellia the skin 

 contains chlorophyll. The muscular coat is thick, 

 striped, with outer circular and inner longitudinal 

 fibres, often netted, and closely attached to the skin. 

 The body cavity is ciliated within. The nervous 

 system consists of an oesophageal ring with a single 

 or double dorsal ganglion (Sipunculus, Sternaspis), 

 sending backward a ventral cord in the body cavity ; 

 rarely outside the muscular lamina (Priapulus). Only 

 in Echiurus are there faint successive swellings on 

 this cord, and in Sipunculus there is a terminal 

 swelling giving off branches. These appearances and 

 the rudimental partitions in the body cavity of Phas- 

 colosoma are indications of metameric division. The 

 ventral cord has a contractile connective sheath 

 (of two laminae separated by soft cells) continued on 

 the lateral branches, which may be irregular, symme- 



