1574 Mr. T. 11. Withers on (he 



tUc rostral end of the capitulnra, especially heiicath such a 

 lartjc wide plate as the rostrum actually is, and in my 

 opinion it is a subcarina, for which there is room between 

 the carinal latcra — otherwise there would be a hiatus 

 between the incurved outer niarj^ins of these valves. 



The capitulum has therefore fifteen valves only of which 

 there is any proof, and, in view of the large size of the lower 

 latera, it is extremely unlikely that there were any more. 

 Had there been more it is quite certaiu that fragments 

 ■would have turned up in the large amount of material that 

 I have examined, for several other specimens exhibit lower 

 lateral valves and in some cases the peduncular plates. 

 While Darwin thought that there were more than three 

 pairs of lower lateral valves, he was of the opinion that there 

 was only a single lower whorl, and, since it has now been 

 shown that there could have been only three pairs of latera, 

 there remains no justification, quite apart from other con- 

 siderations, for the reference of this form, and by inference 

 the related species, to the genus PuHicipes. A restoration 

 is given of the capitulum, and except in the case of the 

 rostrum and subcarina, the exact position of each valve is 

 j)roved by one or other of the specimens discussed here. 



Evidence for this lestoration is just as strong in the case 

 of the allied species Pol/ici/es glaber from the Chalk JNIarl. 

 Precisely similar valves to those known to comj)rise the 

 capitulum of P. unguis have been found detached, including 

 a great number of the peduncular plates, and the absence 

 of any other type of valve, although negative evidence, is 

 strong confirmation of the above conclusion. 



The structure of the capitulum of P. uiif/uis shows that it 

 represents a type distinct from those already known, but, in 

 deference to the views of certain eminent authorities on recctnt 

 Cirripedes, I refrain from making it a distinct genus, and 

 content myself with regarding it as a subgenus of the genus 

 Scalpellum, s. str., definable as below : — 



CUETISCALPKLLUM, SubgeU. IIOV. 



Scalpellids with the upper whorl of valves as in the sub- 

 genus Afcoscalpel/wn, except that the carina is simple (that 

 is, not divided oft" into tectum, parietcs, and intraparietes), 

 and with three pairs of large practically undillerentiated 

 lower lateral valves, of which the infraniedian latus overlaps 

 the rostral and cariual latus on either side ; rostrum excep- 

 tionally large and wide ; peduncular plates large with a 

 smooth, narrow, inwardly-projecting basal ledge. 



iSnhgenotijpe. — SculpcUuia {Cicl'usculpcUuin) unjuis (J. de 

 C. tSowerby). 



