NEW INFORMATION ON CRETACEOUS CRABS 



137 



Fig. 13 Paranecrocarcinus kennedyi sp.nov. Makatini Formation. Barremian. Zululand. South Africa. Reconstruction, based on the holotype. Fig. 7. x ca. 



3, 

 Fig. 14 Rathbunopon ? atherfieldense sp.nov. Lower Greensand. Crackers Bed. Lower Aptian, Atherfield, Isle of Wight. Reconstruction, omitting the 



granulation, based on the holotype. Fig. 9, and paratype. The orbito-frontal margins are diagrammatic, since details of fissures and teeth are not 



preserved, x ca. 8. 

 Fig. 15 Paranecrocarcinus biscissits Wright & Collins. Cenomanian Limestone. Whitecliff, Seaton. Devon. Diagrammatic reconstruction, based on 



specimen in Fig. 10. x ca. 4. 

 Fig. 16 Wilherselta crepitans Wright & Collins. Lower Greensand, Crackers Bed. Lower Aptian, Atherfield, Isle of Wight. Diagram of left frontal margin, 



based on specimen in Fig. 12. x ca. 5. 



matrix and visible only from underneath. The cephalothorax is 

 roughly pentagonal in outline with slightly convex anterolateral, 

 straight posterolateral and slightly concave posterior margins. It is 

 weakly arched in transverse and longitudinal sections, with appar- 

 ently deeply undercut sides. The front is produced into a broad 

 sulcate rostrum, incompletely preserved but showing upwardly 

 directed rostral spines. The orbital margins are not well-preserved 

 but the orbits appear to have been moderately wide with a fissured 

 upper rim and an outer orbital spine; the orbito-frontal width was 

 about half that of the carapace. 



The anterolateral margin ends in a spine at the lateral angle, and 

 there is one between this and the outer orbital spine. The long 

 posterolateral margins are almost straight and converge towards the 

 slightly concave posterior margin. 



The cervical sulcus is bent strongly round the rear of the mesogas- 

 tric lobe and then takes a sinuous oblique course to the margins. 

 Distinct epibranchial sulci branch obliquely to the rear and define 

 small triangular epibranchial lobes. The branchiocardiac sulci are 

 weaker than the cervical and are more or less parallel to it in their 

 outer part; they run back between the small triangular cardiac lobe 

 and a small parallel ridge on either side. 



Discussion. The Hauterivian P. hexagonalis has two large tuber- 

 cles on the mesogastric lobe but no others forward of the cervical 

 sulcus and has a pair of post-rostral slits. The Cenomanian P. 

 mozambiqitensis Forster, 1 970, has a single large tubercle on each 

 protagastric lobe. P. libanoUcus Forster, 1968, from the Cenomanian 

 of Lebanon has a single small tubercle on the mesogastric lobe, two 

 large ones on each protogastric and two smaller ones on each 

 anterior branchial lobe; it also has two post-rostral slits. TheTuronian 

 P.ovalis Stenzel from Texas has an aligned row of large tubercles 

 across the hepatic and protogastric lobes as in P. kennedyi. but the 

 cephalothorax is much broader than long and has a less pentagonal 

 outline, as does the Upper Albian P. graysonensis Rathbun, 1935, 

 with weaker tuberculation. P. digitatus Wright & Collins, 1972, 

 from the English Cenomanian has a pair of post-rostral slits (Collins 

 et al., 1995: 198), and is characterised by its elongated radiating 

 ridges on the protogastric lobes. Pfoesteri Wright & Collins, 1972, 



differs in having strongly granulated posterolateral margins and 

 posterior edges of the branchiocardiac furrows. However, none of 

 these species is known by more than a very few specimens and the 

 extent of intraspecific variation is unknown. 



SOME NEW ENGLISH CRETACEOUS CRABS 



Galathea sp. nov.? 



Fig. 8 



A poorly preserved Galatlwa has been found in Lower Aptian 

 Crackers material from Atherfield, supplied by Prof. W.J. Kennedy. 

 It is inadequate for proper description, but it is worth recording 

 since, with a specimen from the Aptian of Spain (Via Boada, oral 

 communication), it is probably the oldest known species of the 

 genus. 



Rathbunopon? atherfieldense sp. nov. 



Figs 9, 14 



Types. The holotype is BMNH IC 1 1 and paratype IC 12, both 

 from Lower Greensand, Crackers Bed, Lower Aptian, D. callidiscus 

 Zone, Atherfield Point, Isle of Wight. 



Diagnosis. A presumed primitive Rathbunopon, longerthan wide, 

 with the paired bosses at the rear of the mesogastric lobe small and 

 close together; the urogastric lobe feebly developed, divided by a 

 shallow longitudinal groove. 



Description. Small, 7 mm long, about 25% longer than wide, 

 narrowed in front and with slightly convex margins; strongly arched 

 in transverse section, less so in longitudinal; front turned down and 

 deeply furrowed; orbitofrontal margins oblique at about 45°. The 

 furrows delimiting the mesogastric lobe are shallow in front but 

 deepen as they approach the cervical furrow, which is wide and deep 

 laterally. The branchiocardiac furrows are shallower than the cervi- 

 cal. There is a strong circular epigastric boss on either side of the 

 medial furrow, a feeble longitudinal oval one on the anterior process 



