Morphologij of some Cretareous Cirvipedes. 373 



(PI. V. fig. 1) to be the iiirramcdian latus, and it folloivs 

 from this that the otlier valve must be tiie rostral latus. 

 Two similar valves were exhibited apart from each other 

 on speeimen I. 1573 (PI. V. figs. 4a,/'), and these may 

 have belonged to a single individual. In both specimens 

 44300 and J. 1.573 the two valves, although much larger, 

 are exactly similar in structure to ttie two attached valves 

 (Pi. V. fig. 5) figured by Darwin (18."j1, pi. iv. fig. 1 k), 

 and consequently the latter valves are the left rostral and 

 iiifVamedian latu;^, and not right-hand valves as supjjosed by 

 Darwin. ^Moreover, in all the specimens, these two valves 



Sca/pellum (^CretiscalpeJUan) uvyids (J. de C. Sowerby). Albiaii, Gaiilt: 



Folkestone, Kent. Eestoration of capitulum. 



c, carina ; s, scutum ; t, lerguni ; ti.L, upper latus; c.L, carina] latus; 



i.L, infran.edian latus ; r.l., rostral latus ; r, rostrum ; s.c, subcarina. 



show that the rostral latus was not only overlapped by the 

 inframcdian hitus, but the two valves are very similar in 

 shape and size. Consequently, if the rostral latus was 

 placed in position beneath the inframedian latus in the 

 specimen 59802 (PI. V. fig. 1), there would be no room 

 for further latera. 



So far, then, we have proved that the capitulum consisted 

 of a carina, two scuta, two terga, two upper latera, and three 

 pairs of lo\^er latera only, making thirteen valves in all. In 

 addition, we kiiow that there was a large rostrum, and 

 Darwin figured a valve which he called a subrostrum. I can- 

 not conceive how the latter valve could have formed part of 



