159 



They cause a very prominent elevation of the body-wall, like a hump, on 

 both the ventral and the dorsal side of the body. 



The body is comparatively low, with a low frontal area. The preoral 

 band is generally almost straight. A noteworthy feature is the more or 

 less conical shape of the esophagus (especially so in species a). The arms 



Fig. 85. Body skeleton of Ophioplnlrnx urci/er, species a. A. in side view. 280 /i: B. oblique 

 dorsal view. al. anterolateral rod; b. body rod; dm. dorsal median process; e. end rod; 

 pel. posterodorsal; pi. posterolaterul: po. postoral rod; r. recurrent rod; tr. transverse rod ; 



vm. ventral median process. 



are slightly widened at the point. The posterolateral arms are 3 5 times 

 the body length, rather obliquely outwards directed. The other arms are 

 not much more than body length, their point being at about a level with 

 the point of the posterolateral arms. The body skeleton is of the com- 

 pound type. 



Species a. (PI. XXVI, Fig. 1). The posterolateral rods are set with 

 bilaterally arranged small thorns, which give the rod a peculiar, almost 



