Dr. Johnston on the British Aphroditacea. 431 



and with considerable force, from the anus. When placed 

 in fresh water the creature gives immediate signs of its painful 

 situation and soon dies, first ejecting a white milky fluid, 

 and in the agony of death a large quantity of a blackish-green 

 turbid liquor. The size and strength of the proboscis is 

 remarkable, and not less so the structure of the filaments 

 which garnish the orifice. The oesophagus is short ; the sto- 

 mach and intestine seem to be alike and inseparable — together 

 they form a straight intestine, sometimes with a wide dilata- 

 tion in some part of its canal, with a velvety inner surface 

 folded into longitudinal plaits near the termination at the anus. 

 Although apparently planted round with offensive arms of 

 considerable strength, the worm is said to be a favourite prey 

 of the codfish, in whose stomach specimens, in a perfect con- 

 dition, may be sometimes obtained. Baster tells us that the 

 sexes are distinct. u Hae Aphrodites eodem, quo pisces, modo 

 generarevidentur; et si quis earumquasdam Junio mense disse- 

 cuerit, mares lactibus, foemellas multis ovis instructas videbit." 

 Plate XXI. Fig. 1. Jph. aculeata of the natural size. 2. The head 

 uncovered. 3. The head detached and somewhat magnified. 4. Under 

 view of the anterior part of the body. 5. The orifice of the proboscis. G. 

 The proboscis laid open by a longitudinal section. 7. A few of the peni- 

 cillate filaments magnified. 8 and 9. Two views of the feet. 10. Various 

 bristles. 11. The spine. 



2. Polynoe*, Savigny. 



Polynoe is readily distinguished from Aphrodita by the 

 number of the antennae, by the more powerful armature of the 

 mouth, and by the part of the body at which the scales cease 

 to alternate with the cirri. The form of the body, and the 

 number of its component rings, varies much; all our known 

 native species are linear or elliptic-oblong, but there are fo- 

 reign species of a linear and worm-like figure. The back is 

 either entirely covered with the scales or naked in the middle, 

 the scales in the latter being less developed and not meeting 

 on the mesial line. 



The head of the Polyno'es is large and corneous, with four 

 eyes on its upper convex surface arranged in pairs : the an- 

 tennae are rarely two only, three being the usual number, of 

 which the central one is longer than the lateral, and it again 



* Polynoe — one of the Nereids. 



