THE ANNALS 



AND 



MAGAZINE OF NATURAL HISTORY. 



[THIRD SERIES.] 

 No. 64. APRIL 1863. 



XXV. — On the Classification of the Br achy ur a, and on the Homo- 

 logies of the Antennary Joints in Decapod Crustacea. By 

 Wm. Stimpson, M.D.* 



Dr. Strahl lias recently been making some carcinological in- 

 vestigations t, which have led him to propose a new classification 

 of the higher Crustacea. He considers the characters of the 

 external antennae, particularly of their second joint (basicerite) 

 of paramount importance, and would divide the suborder Bra- 

 chyura, in accordance with these characters, into four groups, 

 namely, 



Orbata, with the first two joints of the antenna only present, 

 the rest wanting, as in Acanthocyclus. 



Liberata, with the basicerite free, as in Oncinopus. 



Incuneata, with the basicerite wedged in between the ptery- 

 gostomium and the epistome, as in Cancer. 



Perfusa, with the basicerite completely united with the neigh- 

 bouring parts, as in Stenorhynchus. 



These differences are certainly of great importance, and have 

 not generally received sufficient attention from carcinologists ; 

 but they can scarcely be used for the primary subdivisions, as 

 they are not coincident with characters of still higher value. 

 By their use we should be required to dismember well-marked 

 groups — to separate, for instance, Macrocheira from the Maioids, 

 and Gecarcinus from the Ocypodoids ; while strange approxi- 

 mations would occur, as of Oncinopus with Myctyris. Experience 

 has long since shown us that it is impossible to group animals 

 upon the variations of a single organ. 



Some of Dr. Strahl's conclusions are so surprising that they 



* From Silliman's American Journal for January, 1863. 

 f Monatsbericht der Kbnigl. Akademie dcr "Wissenschaften zu Berlin, 

 1861; Ann. Nat. Hist. vol. ix. p. 299. 



Ann, $ Mag. N. Hist. Ser.3. Vol.xi. 16 



