no. 3645 PORTUNIDAE — STEPHENSON, WILLIAMS, LANCE 15 



Consideration of the results in table 3 and of the models showed 

 that P. sayi @ clearly belongs to the P. pelagicus group; thus, six 

 species in the group were considered. 



Tabular data: Mean values of each species considered separately 

 against the remainder are as follows: 



P. sayi @, NFD 13.0, TD 3.6; P. pelagicus @, NFD 9.2, 

 TD 3.0; P. pubescens (§>, NFD 12.8, TD 3.5; sanguinolentus ©, NFD 

 11.6, TD 3.4; P. convexus @, NFD 11.0, TD 3.3; and P. cf. tri- 

 tuberculatus @, NFD 11.1, TD 3.2. The overall means of NFD 11.5 

 and TD 3.3 indicate a less homogeneous group than either the P. 

 xantusii group or the genus Callinectes. No individual species is close 

 to the "morphological center." 



Inspection of the models: Identical conclusions were obtained. 



General Considerations 



Intergroup and intergeneric relationships. — The critical 

 group is probably the six species in the P. pelagicus group, and this 

 has been considered in relation to the remainder. 



Tabular data: Mean values to other groups are as follows: 



(1) P. xantusii group (15 species), NFD 26.6, TD 5.2. The 

 species in the P. pelagicus group closest to the P. xantusii group is 

 P. convexus @, NFD 23.9, TD 4.9. The species in the P. xantusii 

 group closest to the P. pelagicus group is P. ventralis (%$), NFD 22.8, 

 TD 4.8, closely followed by P. xantusii xantusii ©, NFD 23.7, TD 4.9. 



(2) Callinectes species (12), NFD 17.4, TD 4.2. The species in 

 the P. pelagicus group closest to Callinectes species is P. sanguinolentus 

 <§), NFD 14.5, TD 3.8. The species of Callinectes closest to the P. pe- 

 lagicus group is C. marginatum @, NFD 15.2, TD 3.9. 



(3) Arenaeus species (2), NFD 17.0, TD 4.1. The species of 

 Arenaeus closest to the P. pelagicus group is A. cribrarius @, NFD 16.3 

 TD 4.0. The species of the P. pelagicus group closest to Arenaeus 

 species is P. sayi ®, NFD 11.5, TD 3.4. 



(4) Scylla species (1), NFD 20.3, TD 4.5. The species of the 

 P. pelagicus group closest to Scylla is again P. sayi ®, NFD 16, TD 4. 



These values show : (1) The P. pelagicus group is much further 

 from the bulk of the American species of Portunus (the P. xantusii 

 group) than it is from Callinectes, Arenaeus, or Scylla. (2) The degree 

 of separation of Arenaeus, plus Callinectes, from the P. pelagicus group 

 is greater than the average separations between the members of this 

 group; hence, the genus Portunus stands apart from these two genera. 

 (3) Scylla is even more distant from the P. pelagicus group. (4) The 

 most doubtful of the classical separations is that between Arenaeus 

 and Callinectes. While Callinectes species form a homogeneous entity 



