ASTKMMA. CEPHAI.OTRIX. 19 



species, it is the orifice tlirough which a very long proboscis can be 

 evolved. The intestine runs undivided through the length of the 

 body ; and, it seems probable, that, in all, there is an anus. This 

 has been demonstrated in a few species. It is found in some open- 

 ing well forwards on the ventral surface, and in the posterior extremity 

 in others. There is another, and much larger, aperture in front, 

 behind and underneath the head. Long mistaken for the mouth, 

 this has been usually described of late as genital, but the office is 

 doubtful. In a few genera there are fissures on the sides of the 

 anterior end, which are neither respiratory nor ovarian, as has been 

 supposed. — All are marine, and are readily distinguished, in their 

 order, by their length, which exceeds the breadth considerably, and, 

 in many instances, "far o'ersteps the modesty of nature." The ova 

 are laid enveloped in a jelly. 



12. ASTEMMA. 



Astemma, Oersted, Entw. Plattw. 82. 

 Char. Acephalous, the body filiform, vnthout eyes or fissures on 

 the sides of the anterior extremity : mouth inferior, approximated to 

 the front : anus terminal ? 



1 . A. rufifrons, yellowish, verging on rose-red anteriorly ; the front 

 obtuse, dark red. Length 2-3" ; breadth i'". 



Borlasia (Nemertes) rufifrons, Johnston in Mag. Zool. Sf Bot. i. 538. 



pi. 18. f. 4, 5. Dies. Syst. Helm. i. 241. 

 Astemma rufifrons. Oersted, Entw. Plattw. S2. f. 13. 

 Gordius gracilis, Dalyell, Pow. Great, ii. 74. pi. 9. f. 8-11. 



Hab. Under stones, and amidst algae, between tide-marks, 

 (a) Berwick Bay, Dr. Johnston. 



2. A. filiformis, white or cream -yellow, thickened in front. Length 

 1-2". 



Planaria filiformis, Johnston in Zool. Journ. iv. 56. 

 Borlasia? filiformis, Johnston in Ann. Sf Mag. Nat. Hist. xvi. 434. 

 pi. 15. f. 1 a, b. Dies. Syst. Helm. i. 242. 



Hab. Under stones, in muddy places, between tide-marks. 



13. CEPHALOTRIX. 



Cephalotrix, Oersted, Entw. Plattw. 81. Dies. Syst. Helm. i. 246. 



Char. Acephalous, the body filiform or flattish : mouth anterior, 

 ventral : no lateral fissures : eyes two, placed in front on a parallel 

 line. 



I . C. lineatus, filiform, narrower at each end, dark-grey, ruddy in 



c 2 



