
34 FOSSIL CIRRIPEDIA. 
elongated, attached to Sponges, or rarely to the bark of Isis: scutum and tergum articulated 
together, subtriangular. 
Under the last genus, I have made a few remarks on the close affinities of this sub-genus 
to Balanus, and have given my reasons for retaining it, so that I need not here 
repeat them. 
Acasta unvuLata. ‘Tab. II, fig. 6a—6/. 
A. testi, ad speciem, ut in “ A. spongites,” sed majore: scuto externe striis longitudi- 
nalibus, sepe binis, signato, sulcis intermedius latioribus: tergi calcare, pene 3 valve 
latitudine. 
Shell, apparently, as in A. spongites, but larger: scutum marked by longitudinal ridges, 
often in pairs, with the intermediate furrows rather wide: spur of tergum nearly half as 
wide as valve. 
Fossil in Coralline Crag (Sutton), Mus. S. Wood, Bowerbank. 
I owe to Mr. Wood the inspection of a fine suite of valves, which, though separate, I 
have no reason to doubt have all been rightly attributed to the same species. Owing to the 
shell never having been found entire, its general shape is not known, and, what is of more 
consequence, the relative proportional width of the parietes of the carmo-lateral compart- 
ment is unknown. I have (but with doubt) given it a distinct specific name, owing to the 
peculiar character of the furrows on the scuta, and to the large size of the whole shell. In 
its other characters it comes nearest to A. spongites, excepting in the spur of the tergum, 
which resembles that of 4. sulcata. 
The external surfaces of the compartments appear generally to have been smooth; but 
in several specimens they are studded with the sharp shelly points so common in the 
genus. A rostrum (I'ab. II, fig. 6a), and lateral compartment (fig. 66), have been figured. 
The radii are not wide. The basis (fig. 6c) is cup-formed : its edge is either quite smooth, 
or is very finely crenated. ‘The basis is sometimes quite irregularly perforated, as in the case 
of several recent species, by numerous minute orifices, which, when the animal was 
alive, no doubt were covered by membrane. Internally the parietes are feebly ribbed, as 
in A. spongites. Judging from the dimensions of the separated valves, this species must 
have equalled and perhaps exceeded in size the largest living species, namely, 4. glans, from 
Australia. Hence we may infer, that the basal diameter probably exceeded 55 of an 
inch: I may add, that the largest European specimens of 4. spongites, from Naples and 
Portugal, are only ‘3 of an inch in basal diameter. 
Scuta (fig. 6e).—These seem to resemble the scuta of 4. spongites in all respects, except 
