84 FOSSIL CIRRIPEDIA. 



latera. The consequence of this arrangement is, that in the alternate whorls there are 

 in one, four of the large lateral scales and none of the smaller end scales ; and in the 

 whorl, both above and below, only two of these large lateral scales, and four of the carinal 

 and rostral scales ; so that the alternate whorls (fig. 4) had an unequal number of scales, 

 namely, four and six. 



Growth. — New scales for the peduncle are formed round its upper edge, at the bases 

 of the valves of the capitulum, the chief growth of which, as we have seen, is downwards : 

 hence, we here have, as in other pedunculated Cirripedia, a principal line pf growth round 

 the summit of the peduncle. It can be seen that a new scale is first formed under the 

 second latus, at the carinal end of the peduncle ; and this agrees with the fact that there 

 is one more scale in this row than in that next to it ; and one more in the latter, than in 

 the row under the scutum. I may mention, as in conformity with this fact, that in the 

 development of the young of Scalpelliim vul(/are from the larval condition, the calcareous 

 scales on the peduncle first appear under the carina. 



Attachment. — With respect to the attachment, Mr. G. B. Sowerby seems to have felt 

 great difficulty on account of the peduncle ending in so fine a point ; but the peduncle 

 of Scalpellwm vulgare, when carefully dissected from the coralline to which it is attached, 

 often ends in a much finer point, and is symmetrically attached to the branch by its 

 narrow rostral margin. In Loricula, the attachment was probably by one lateral face of 

 the lower part of the peduncle ; for it is by no means unusual for the cement-stuff" (even 

 when proceeding only from the two original central orifices, where the prehensile antennae 

 of the larva may still be found) to encroach largely on the peduncle, and thus fix it down. 

 The calcareous scales of Pollicipes, and the horny spines of Ibla, may often be found thus 

 embedded and firmly fixed to the supporting rock ; it is moreover possible, that in Loricula 

 the cement was poured out of orifices, specially situated on one side of the peduncle, as 

 takes place along the rostral margin in Scal^ellum vulgare, and high up on both sides of 

 the peduncle in Lepas fascicularis. 



Dimensions. — Entire length of the specimen rather above one inch : width of widest 

 part of the peduncle "6 of an inch. 



On the probable condition of the 8p>ecimen ichen perfect. — I have already remarked 

 that the three valves of the capitulum, and the five rows of scales on the peduncle, must 

 have had an opposite series. I at first thought it extremely improbable that the animal 

 should have been split so exactly down the middle ; and I conceive, in most genera, as in the 

 common Lepas, it would be quite impossible to effect this ; but in removing the tcrga and 

 scuta from one side of several specimens in Ibla and Lithotrya, it was difficult to prevent 

 exactly half of the membrane of the peduncle (which in these genera is thhi) being torn 

 off with them. Mr. G. B. Sowerby, jun., also has remarked (Annals of Nat. Hist., 1843, 

 p. 261), that, owing to the rostral and carinal rows of small scales not intersecting each 

 other, the splitting of the specimen into halves along this plane would be much favoured. 

 The inner edge of the so-called second latus could not have touched the inner edge of its 



