KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 40. N:0 4. 13 



25 longitudinal rows of soft, pointed papillse. Wall of the trunk with superficial 

 circular ridges. Mouth terminal, armed with series of powerful, pectinate, härd teeth. 

 Arms terminal. External anal appendages present or not. Intestinal canal straight. 

 Retractor nmscles present. Segmental organs or uterine pouches absent. Two sacci- 

 form genital glands, opening posteriorly ventraly to the anus. Interna! rectal or 

 cloacal appendages or »nephridia» absent. 



Pr ia pulas (Lamarck 1816). External anal appendages present. Longitudinal muscle 

 layer of the body wall in separate bands. 8 long and 10 — 14 short retractors. 



Anal appendages: one P. caudatus (Lamarck 1816). 



two P. bicaudatus Danielssen, 1869. 



Halkryptiis v. Siebold 1849. Externa! anal appendages absent. Longitudinal muscle 

 layer of the body wall forming a continuous layer. 10 short retractors 



H. spinulosus v. Siebold, 1849. 



Sub-Order Echiurida. 



Front al hood or proboscis well developed. Tentacles, teeth, external anal 

 appendages and retractor muscles absent. A pair of strong genital setae, or 

 two prominent genital papillae, anteriorly on the ventral surface. Bristles poste- 

 riorly present or not. Body elongate, cylindrical or sacciform, devoid of longitudinal 

 and transverse ridges. Mouth and anus terminal, the former at the base of the pro- 

 boscis and ventraly to it. Intestinal canal not straight, forming a number of circum- 

 volutions. Uterine pouches or segmental organs present in one or several pairs — 

 except in Bonellia which has a single one — . 1 Genital glands unpaired accompaning 

 the nerve cord. A pair of branched or unbranched interiör cloacal appendages or 

 nephridia. ~ 



* Bristles present surrounding 

 in t\\<> somewhat iiTegiilar circles the posterior extremity of the body. 



Echiurus Pallas 1774, Cuvier 1830. Frontal hood or proboscis simple, broad, gutter- 

 or shovel-shaped. Two strong genital setae. Commonly two pairs of uterine 

 pouches or segmental organs. Cloacal appendages simple sacs. Shape of the 

 body cylindrical. 



E. Pallasii Guerin, 1829—1843. 



1 Kat Laxkesteu. it i- trut. relätes that the one of hi- two specimens of Hamingia arctica was in pos- 

 session of a single -uterine pouch», but like Skobikow (1901) I believe this to be an abnorma] case. 

 ä In the characteristics no consideration is taken of the ininute males. 



K. Sv. Vet. Akad. Handl. Band 40. N:o i. - 



