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MUNIDOPSIS BAIRDIL 



83 



connected from the latter genus in the absence of transitional species. Gala- 

 t/iodes, Oroplmrrliynchusj and Elasmonotus^ on the contrary^ arc bound by a 

 perfectly graduated series of numerous connecting forms with the typical 



Miuiidoii 



# 



In the large and plastic genus Munidopsis, evolution has progressed along 



F 



several lines of species^ and for the purposes of a monographer it may be 

 nseful 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 suhgenus^ in which we see a genus in the process of 

 forming, as it were. By the more or less comiDlete 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.! 

 Viewed in this light, subgenera may plaj a very useful part in a philosophi- 

 cal system of nomenclature. 



Munidopsis bairdii Smith. 



Oalacantha bairdii Smith, Proc U. S. Fisli Comm. for 1882, p. 35G, 1884. 



Mmidoims bairdii Smith, Proc. U, S. Nat. Mus., VII. 493, 1884 • Ami. llcp. U. S. Fisli Comm. for 

 1885, p. 649, Plate V. Fig. 2, 1880. 



Station 3381. 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 lias three spines on the right side, two 

 on the left j the body is slenderer. The differences are perliaps partly indi- 

 vidual, partly sexual, Smith's description and figure having been made from 

 a female specimen. 



* Professor Iloudcrson iu 1885 (Ami. Mag. Nat. Hist,, 5tli Ser., XVI. 417) proposed tlio genus Galatho^- 

 us as a reliige for certain species intermediate between Mmddopm and Elasmorioius. This only added to tlie 

 didieulty by drawing two arbitrary lines of division in place of one. In his final report on the " Challenger" 

 Anoniura, Henderson suppressed the genus Galathopsis and assigned the intermediate species to i'famo^c,/^.., 

 exiircssmg at the same time his grave doubts coueerniug the separability of Etamomlus from Munidopsis 

 (Challenger Anomnra, pp. 158, 1C5). It is of interest in this eonneetion to note that Milne Edwards and Bou- 

 vier (op. eit., p. 283) incline to place these same species in Mmudopsis rather than in Ela^momtm^. 



t The Code of Nomcnelature and Check-List of North Auicrieau Birds adopted by the American Orni- 

 thologists' Uuiou, being the Report of the Committee of the Union on Classification and Nomcnelature, p. 31. 

 New York, 188G. 



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