MUNIDOPSIS BAIRDII. 83 
connected from the latter genus in the absence of transitional species. Gala- 
thodes, Orophorrhynchus, and Elasmonotus, on the contrary, are bound by a 
perfectly graduated series of numerous connecting forms with the typical 
species of Munidopsis.* 
In the large and plastic genus Munidopsis, evolution has progressed along 
several lines of species, and for the purposes of a monographer it may be 
useful to assign names to the extremes of modification found within the 
limits of the genus, in order that the interrelations of the species may be 
brought into view. This is the function, as I understand it, of the category 
of classification known as subgenus, in which we see a genus in the process of 
forming, as it were. By the more or less complete extinction of interme- 
diate species we may assume that genera of the present have come from 
subgenera of the past, and that future genera will be evolved from sub- 
genera of the present. I would distinguish between genera and subgenera 
much as the American ornithologists do between species and subspecies.t 
Viewed in this light, subgenera may play a very useful part in a philosophi- 
cal system of nomenclature. 
Munidopsis bairdii Smrru. 
Galacantha bairdii Smitu, Proc. U. 8. Fish Comm. for 1882, p. 356, 1884. 
Munidopsis bairdit Smiru, Proc. U. 8. Nat. Mus., VII. 493, 1884; Ann. Rep. U. 8. Fish Comm. for 
1885, p. 649, Plate V. Fig. 2, 1886. 
Station 3581. 1772 fathoms. 1 -male. 
Differs from the type, as described by Smith, as follows: the central pair 
of spines of the gastric area and the anterior pair of spines of the cardiac area 
are absent ; the rostrum has three spines on the right side, four on the left ; 
the posterior margin of the carapace has three spines on the right side, two 
on the left ; the body is slenderer. The differences are perhaps partly indi- 
vidual, partly sexual, Smith’s description and figure having been made from 
a female specimen. 
* Professor Henderson in 1885 (Ann. Mag. Nat. Hist., 5th Ser., XVI. 417) proposed the genus Galathop- 
sis as a refuge for certain species intermediate between Munidopsis and Elasmonotus. This only added to the 
difficulty by drawing two arbitrary lines of division in place of one. In his final report on the “ Challenger” 
Anomura, Henderson suppressed the genus Ga/athopsis and assigned the intermediate species to Z/asmonotus, 
expressing at the same time his grave doubts concerning the separability of Zlasmonotus from Munidopsis 
(Challenger Anomura, pp. 158, 165). It is of interest in this connection to note that Milne Edwards and Bou- 
vier (op. cit., p. 283) incline to place these same species in Munidopsis rather than in Elasmonotus. 
+ The Code of Nomenclature and Check-List of North American Birds adopted by the American Orni- 
thologists’ Union, being the Report of the Committee of the Union on Classification and Nomenclature, p. 31. 
New York, 1886. 
