XV 



EPITHETOSOMATOIDEA 



445 



of the proboscis is the mouth ; the intestine is straig 



terminates in the anus, which is posterior. The nervous 



lies between the circular and the longitudinal 



muscles of the body-wall, and contains a 



tube, the nature of which is obscure. No 



vascular system is known. The ovary is 



attached to a mesentery ventral to the 



anterior part of the alimentary canal, and 



there is a single nephridium. No anal 



vesicles exist. 



The most remarkable feature of the genus 

 is a series of pore-like openings, which are 

 stated to lead from the outside into the 

 body-cavity (Fig. 225, a). These are 

 arranged four on each side, at the bottom 

 of two slit-like depressions in the skin, 

 which lie one on each side of the base of 

 the proboscis, slightly dorsal to it. 



These remarkable structures are with- 

 out parallel amongst the Gephyrea, and, 

 together with the peculiar character of the 

 proboscis, justify the Norwegian naturalists 

 in adding a new family to the group. 



ht, and 



system 



Affinities of the Gephyrea. 



Fig. 225. A, Epithetosoma 

 norvegicum K. and D., 

 magnified, a, a, Right 

 and left slits leading to 

 the pores ; b, mouth ; c, 

 proboscis : B, the same 

 animal opened dorsally ; 

 a, pores ; b, oesophagus ; 

 c, proboscis ; d, brown 

 tube. (After Danielssen 

 and Koren. ) 



Before considering to what other groups 

 of animals the Gephyrea may be allied, it is 

 advisable to discuss the relationship of the 

 four Orders which compose the group. 



Quatrefages, in the year 1865, divided 

 the Gephyrea into I. Gephyrea Armata, 

 with which he included the Echiuroidea 

 and Stemaspis} and II. Gephyrea Inermia 



or Sipunculoidea. The Gephyrea Inermia, sometimes called the 

 Achaeta, have been extended to include the Order Priapuloidea, 

 and opposed to the smaller sub-group the Gephyrea Armata or 

 Chaetifera. In my opinion, however, these names now are no 

 longer in accordance with our knowledge of the structure of the 



1 Vide p. 335. 



