506 



verfcly : fometimes it has a flight, longitudinal farrow, 

 on each fide, forming a ridge, or carina, along the back. 

 Diameter a quarter of a line. 



This, very minute fpecies, is alfo an heteroclitical 

 fhell, and not eafily diftinguiflied from S. Iietcro/lropha, 

 except by its inferior fize, rounded bafe, and habits : 

 this affefts only the Corallina officinalis, (Ellis Coral. 

 tab. 24. f. 2. and Zoophytes, tab. 23. fig. 14. 15.) fre- 

 quently in abundance, both on (talks and branches. 



This Coralline is plentiful on the rocks about Mtlton, 

 which are partly of the fame flaty nature, on which Ser- 

 pula lictcrojlroplia is found; but none of that fpecies oc- 

 cur on the rocks contiguous to this Coralline ; indeed the 

 S. heterojiropha is rarely expofed, but lies concealed, af- 

 fixed to the under part of the loofe. flat, flate ft;ones: this, 

 on the contrary, is always expofed to the rude a6lion of 

 the waves. 



The young of this, as well as moft of -the longitudi- 

 nally fulcated, or ribbed fpecies, are quite fmooth, and 

 may be eafily mifl;aken. 



Animal a Terebella, with ciliated feelers, and clavated 

 probofcis, varying in colour from brown to green. 



I 



10. 



■ Serpula reflexa. Lin. Trans, v. t. 1. f. 31. 32 ? (Adams.) 

 Turt. Liu. iv. p. 603. 



■ Serpuk 



