14 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 124 



Inspection of the models: The models show the genus as a close- 

 packed group. In the first figured model (figs. 1 and 2) C. gladiator 

 ®> and C. marginatus @ are the most peripheral species. This differs 

 somewhat from the results of the tabular data, in which C. bellicosus 

 % and C. marginatus @ were the most peripheral species. The second 

 figured model gives a closer approximation to the tabular data, with 

 C. marginatus @ as a peripheral species. The "incenter" in the first 

 figured model lies approximately equidistant from C. boucourti (g§), 

 C. danae @, and C. ornatus @; in the second model, the "incenter" 

 lies approximately midway between C. arcuatus @, C. bellicosus ®, 

 and C. boucourti @). These results differ from the tabular considera- 

 tion, in Avhich C. latimanus @ was the "focal" species. It is considered 

 significant that most of the postulated "central" species occur in the 

 Atlantic, and it is conceivable that the group originated from an 

 eastern American ancestor. It seems virtually certain that the western 

 American forms arose from eastern American ancestors. 



PORTUNUS PELAGICUS @ AND RELATED SPECIES OF PoRTUNUS. Five 



species are known on classical grounds to be related closely, forming 

 a P. pelagicus "group": P. pelagicus @, P. sanguinolentus @, P. 

 pubescens <H>, P. convexus @, and P. trituberculatus @. 



Neptunus madagascariensis Hoffman, 1874, has not been included 

 in this group in spite of its obvious resemblance to P. sanguinolentus 

 @, which has been commented upon by both Hoffman (1874, p. 8) 

 and Crosnier (1962, p. 47). Crosnier put the species in the genus 

 Portunus. Hoffman, however, stated in his description that it differed 

 from Neptunus diacanthus Latreille, 1825, only in "Fabsence de 

 lupine sur le bord posterieur du bras. Cette difference est tellement 

 minime que cette espece ne forme peut-etre qu'une varidte" de Nep- 

 tunus diacanthus." The varieties of N. diacanthus of Hoffman's time 

 are now species of Callinectes, and Miers (1886) has suggested already 

 that N. madagascariensis belongs to Callinectes. It possesses the fol- 

 lowing diagnostic features of that genus: an tero external angle of 

 merus of third maxillipeds expanded and wrist of cheliped without 

 inner spine. The absence of a spine on the posterior border of the arm 

 is shared with C. exasperatus @ although the species keys out from 

 Rathbun (1930) as G. danae @. It is unfortunate that this most 

 interesting species is known only from the holotype female, whose 

 present location is unknown. 



Stephenson (1968, in press) recently has obtained evidence of the 

 existence of an undescribed subspecies of P. sanguinolentus @. This 

 has been omitted from present consideration because it is identical 

 with normal P. sanguinolentus @ on the basis of the list of features 

 that are used herein. 



