SPIONIFORMIA. 



483 



Sub-order 2. SPIONIFORMIA. 



Without tentacles or palps ; the peristomium usually carries a pair 

 of long tentacular cirri, and extends forwards at the sides of the 

 prestomiuni. The parapodia project but slightly ; the dorsal cirri 

 may attain a considerable size, and act as gills throughout the greater 

 part of the body. The setae are unjointed ; uncini are present only 

 in Cliaetoptems. 



The body may present two regions more or less distinctly marked 

 externally, but without corresponding internal differences. 



The buccal region may be eversible, but there are no jaws. Septa 

 and nephridia are regularly developed. The worms burrow or are 

 tubiculous. 



Fig. 395. Chaetopterus peryamentaceus Cuv. = variopedatus Ren. 

 (Regne Animal), in its tube, which is partly laid open. 



Fam. 1. Spionidae. Prestomiuni small, without tentacles or palps, though 

 sometimes with tentaculiform projections, usually with small eyes. Peristomium 

 extends forward on each side of the prestomium, and bears two long tentacular 

 cirri. Parapodia generally biramous, with simple setae. The notopodial cirri 

 are long, finger-shaped, and ciliated, and function as gills. There are no ventral 

 cirri. The buccal region is eversible. They burrow in mud and sand. The 

 females lay their eggs in the tubes. Polydora Bosc. (Leucodore Johust.). Pre- 

 stomium with two tentaculiform projections. The 5th setigerous segment is 

 enlarged, and bears specially strong setae arranged in a comb-like manner. 

 P. ciliata Johust. , in soft mud tubes in U-shaped galleries in stones and 

 shells ; length i-inch ; 40 segments ; anus surrounded by incomplete funnel ; 

 world-wide; P. coeca Oerst. Spio Fabr., S. seticornis Fabr., Greenland and 

 .Scandinavia ; Prionospio Mlg. ; Scolecolcpis Blaiuv. ; Nerine Johnst. ; N. vulgaris 

 Johnst., under stones and on seaweed, 3 or 4 inches long, N. Atlantic. 



Fam. 2. Chaetopteridae.* Body divided into two or three unequal regions. 

 Prestomium small, often with eye-spots. Peristomium prolonged round the 

 mouth in a funnel-like manner, and bearing two or' four tentacular cirri. The 

 fourth segment behind the peristomium with specially strong setae as in Poly- 

 dora. Neuropodia bifid in the posterior region, and sometimes in the middle 



* Joyeux-Laffuie, Arch. Zool. Exp., (2), 8, 1890, p. 244. 



