.NOTES ON GENERA. 123 



arm. Two of the fossil species of Fentagonastcr, namely 1'. hiudtus and obliisiis, 

 have all arms which are well produced (the arms in the specimen of P. lunatus 

 figured on PI. IV, fig. 1, are broken off short). The third and remaining species, 

 1'. qiiinqaeloha, is usually much more pentagonal in shape, although a specimen in 

 the possession of Dr. Blackniore has a major radius at lea,st twice the magnitude 

 of that of the minor radius. 



The species assigned to the genus Nym2)hash'r by Sladen were so assigned 

 because their structure and character, so far as they could be made out from the 

 fragmentary condition of the fossils, appeared to warrant their inclusion in the 

 genus Xi/niphasfcr (see jd. 15). 



It appears to me that these species have the same generalised characters as 

 those assigned to the genera L'alliderma and rentiujonanter. The distinctive 

 character of the genus Nijmpknster is the possession of paxilla? on the abactinal 

 plates. No fossil species is suflBciently well preserved to show whether these were 

 absent or present, and it is impossible therefore to confirm or deny Sladen's 

 suggestion. 



DO 



It will be seen from the above tliat there is no certain evidence which entitles 

 us to distribute the Cretaceous species amongst the three genera, and it may be 

 the task of a future observer to phice tlieni in one new genus. I luive, however, 

 in order to secure uniformity, utilised all these generic names even for the 

 description of new species. The following species also appear to re(iuire revision. 



Callidenna Smithiae, C. mosaicum. 



After examination of the fairly numerous specimens of the fossils assigned to 

 these species in the British Museum (Nat. Hist.) I cannot confirm the specific 

 distinctions made by Sladen on pp. 10 and 11 of this Monograph. All the 

 characters mentioned vary greatly in individual specimens. The ornament, 

 however, is common in character to both species, and I should prefer to unite them 

 in one species, namely, C. Smithiai, as this has prior place in the original account 

 given by Forbes. 



The specimens figured on 1*1. VII, figs. 1 and 2, and stated by Sladen to be in 

 his opinion doubtful examples of iV. Coombii (p. 17), should in my opinion be 

 assigned to C. Smlthix, as should also the specimen figured on IM. XIX, fig. 3. 

 The.se examples po.ssess a finer type of honeycomb structures on their marginalia 

 than is usually met with in G. Smithisc, and they may, therefore, be a distinct 

 variety of this species (see Text-fig. 8). 



A specimen preserved in the British Museum (Nat. Hist.) E. oOG3, was figured 

 by Sladen on I'l. V, fig. 1 ", of this Monograph as Tuinidotitcr sulca(n.s. Apparently 

 it was the intentiuii of Sladen to make a new genus and species for the rece])tion 



