42 BALANJDJE. 



therefore cannot confirm the above analogical conclusion, 

 namely, that they, also, belong to a lower whorl. 



In the sub-family Balaninse, which includes Balanus 

 (woodcut 7), and Tetraclita (woodcut 8), the shell is charac- 

 terised by not having rostro -lateral compartments, and by 

 the rostrum having radii : now in Tachylalia giganteum, 

 which undoubtedly belongs to the sub-family Chthamalinse, 

 at a very early age the rostro-lateral compartments become 

 blended with the true rostrum, making a compound ros- 

 trum, exactly like the rostrum in the Balaninse ; distinct 

 evidence of a similar fusion is retained throughout life 

 (PL 15, fig. 1) in all three species of Chelonobia, which is un- 

 doubtedly a member of the Balaninse. Hence, I think, we 

 may conclude that in all the genera of the Balaninse the 

 rostro-lateral compartments are probably not aborted, but are 

 blended with a normal rostrum (resembling that in wood- 

 cuts 4, 5, 6), making together a compound rostrum fur- 

 nished with radii : it must, however, be observed that I could 

 not detect any actual evidence of this fusion in Balanus, 

 even immediately after the metamorphosis. In Chamsesipho 

 (woodcut 6), either the rostro-lateral compartments attain a 

 most unusual breadth, or, as is more probable, they have 

 become confluent with the lateral compartments, which in the 

 Lepadidse seem to be the most persistent of all the lateral 

 valves. In such genera as Tetraclita and Chthamalus, in which 

 the carino-lateral compartments are absent, they may be 

 fused with the lateral compartments or with the carina ; but 

 seeing that they are normally developed later than the other 

 valves, it appears to be the simplest theory to assume, until 

 the contrary be proved, that they are aborted. Finally, the 

 somewhat unexpected conclusion that the shell (not includ- 

 ing the operculum) of sessile Cirripedes normally consists of 

 eight valves, four belonging to an upper whorl, and four 

 to a lower whorl, all forced into a single. ring, and often 

 more or less fused together, though not strictly proved, is 

 rendered highly probable. I will only further add, that 

 the Basis perhaps represents several whorls of the small 

 valves or scales on the peduncle of Pollicipes, fused together; 

 the comparison of the basis with the calcareous cup, 

 forming the lowest portion of the peduncle in Lithotrya, 



