246 APPENDIX. 



he had abundant opportunities when voyaging in the southern 

 Pacific. He maintains that it is neither an Acalephe as sup- 

 posed by Chamisso, or a Pteropod as conjectured by Martins, but 

 one of the Timicata, of which group it is the lowest form, con- 

 nected on the one hand with the Salpte, and on the other with 

 Pelonaia, and representing permanently the transient tadpole 

 condition of the Ascidian larva. 



The shape of this minute creature is that of an oblong body, 

 furnished with a long curved compressed lanceolate tail or fin ; by 

 the vibrations of this latter organ it propels itself rapidly through 

 the water. 



This brief and imperfect notice of its existence in the British 

 seas may call attention to it, and induce some of our zoologists to 

 search for and investigate our native species. 



AOEPHALA LAMELLIBRANCHIATA. 



Vol. i. p. 66. Teredo Nokvagica. 



Mr. Cocks, of Falmouth, writes us word, that this iisually 

 scarce species in England is only too prolific in his neighbour- 

 hood ; the piles and the wood-work of the quay being replete 

 with shipworms. " I have been informed," he continues, " by 

 several sailors, that the worm is common in the mud creek 

 between Flushing Passage and Penryn (both in the immediate 

 vicinity), and that ships and wood allowed to remain long in 

 that situation are sure to be attacked by the worm." 



Vol. i. p. 74. T. NAVALIS. 



The piles of the signal-posts upon the rocks near St. Peter's 

 Port, Guernsey, were found perforated by this rare ship-worm. 

 (S. H.) 



Vol. i. p. 77. Teredo megotara. 



" Animal vermicular, pale bluish-white, inclosed in a subcyliu- 

 drical elongated tubular mantle, not of very thin texture, only 



