256 SKRPULID.«. 



erecta radicata," — contrasted with the character of the Serjmla — 

 "testa teretiuscula recta basi flexuosa," — a]»pears to prove that Eas- 

 ter's species was the object he had immediately in view when he 

 pubUshed his 12th edition in l/t)/. The other synonyms, however, 

 may render this inference of mine disputable ; and it is safer to 

 adopt the name ventilabrum, — the one applied to the species by 

 Gmelin, and generally adopted. 



Although common on the British coasts, the worm was not de- 

 scribed as a native until by Mr. Montagu in 1804 or 1805*, who, 

 however, did not dispute its identity with the Mediterranean worm, 

 and attributed all the differences between them to geographical posi- 

 tion, and to the action of the spirits in which the foreign specimens 

 were preserved. The " extreme elegance " of the worm he dwells 

 on with pleasure ; and he correctly tells us that the filaments of the 

 branchife are " ciliated on both sides," appearing only semipectinate 

 when in a state of contraction, or when plunged in spirits. His de- 

 scription of the tube is excellent. 



The life of this species is an interesting history. Analogy leads 

 us to believe that the eggs, involved in a mass of jelly, are extruded, 

 in their season, from the upper aperture of the tube. Nourished in 

 the jelly, they rapidly pass through the foetal metamorphoses, and 

 attain the annelidan form so soon as they are free, or, at least, before 

 they are more than 2 lines in length. The first instinct constrains 

 and enables the infant worm to build, out of the mud around it, a 

 tiny case to shield the body ; and this is in future always carried 

 onwards as an advanced work, so as rather to receive the body as it 

 grows in size than to wait upon that growth. The growth is rapid ; 

 and the external organs, as well as the rings of the serpentine abdo- 

 men, are evolved in succession. Thus the worm has at first few 

 segments, and the ornaments of the head may have no more than 

 six filaments. These too are, on their first ajjpearance, simple ; and 

 it is a subsequent development that fringes them with cilia, and 

 makes the organ pectinated. When mature, a well-fed specimen 

 may have 92 filaments in each of the fans of the branchial tuft that 

 adorns the head ; and the body may consist of not fewer than 350 

 rings, each with their pair of pencilled feet, and ringlets of many 

 booklets. Such a specimen will be 15 inches in length ; and the 

 tube will be 2 feet. 



The tube is essential to the existence of its tenant. The part first 

 formed, to fit it for its purpose, is necessarily of small calibre, and it 

 is laid horizontall3^ The inmate protrudes its posterior extremity 

 from beyond the lower end of the tube, and fixes it to any adjacent 

 object or support by a glutinous secretion furnished apparently by 

 the anal segment, which, according to Dalyell, is glandular. When 

 the tube has been thus anchored, the entire attention of the worm is 

 directed to its anterior end, which is raised up in a more or less erect 

 posture by continual and incessant additions to the rim of the aper- 



* The first part of his work was published in 1803, and I find no date to the 

 second part. 



