THE VOYAGE OF H.M.S. CHALLENGER. 
viii 
The remainder of the Anomnra (Hippidae, Paguridae, Galatheidse) are included by 
Dr. Claus in the Macrura. 1 
Dr. E. Nauck, in 1880, 2 who based his classification on the solid stomachal plates of 
the Brachyura, proposed to divide this group into the following sections : — 
I. Heterodonta (to include the Gelasimidao, &c., and Pinnotheridse). 
II. Cyclodonta ; subdivided as follows : — 
A. Coelostylidea, including the Catometopa of Milne Edwards (except the 
Gelasimidae and Pinnotheridse), and the Oxyrhyncha, Milne Edwards. 
B. Platystylidea, including the Oxystomata, Milne Edwards; and Cyclo- 
metopa, Milne Edwards. 
Trapezia, in which the structure of these parts is very peculiar, is separated from 
the remainder of the Cyclometopa and establishes a connecting link with the 
Heterodonta. This classification is not very natural or convenient, and is not 
followed by M. F. Mocquard in his elaborate memoir referred to above. 
By J. E. Y. Boas, 18 80, 3 the Dromiidse are included with the Brachyura, and the 
group is divided into (a), Brachyura genuina ( = Brachygnatha, de Haan, except the 
Dromiacea and the Oxygnatha) and (b), Dromiacea. This author regards the group 
Oxystomata as of doubtful value. 
In the classification adopted in the following pages, a synoptical view of which is 
given below, the arrangement followed is generally that of Professor Dana, so far as the 
leading subdivisions are concerned. 
In subdividing the Oxyrhyncha, I have adopted the arrangement indicated by myself 
in a memoir submitted to the Linnean Society in 18 79. 4 
As regards the Cancroid Cyclometopa, I have followed Professor A. Milne Edwards in 
his monograph, unfortunately never completed, of the Canceridae, 5 in not sustaining 
Dana’s family Eriphiidse, but have not ventured to propose any detailed classification of 
the genera which are not very numerously represented in the Challenger collection. The 
Trapeziinae, which are placed in a separate section, should probably rank as a distinct 
family intermediate between the Cyclometopa and Catometopa. 
As regards the swimming crabs (Portunidae), I follow A. Milne Edwards 6 in uniting 
1 This classification has been followed by J. V. Cams in his recently published Prodromus Faunae Mediterraneas 
(Arthropoda), Stuttgart, 1885. 
2 Das Kaugeriist der Brachyuren, Zeitschr.f. wiss. Zool., Bd. xxxiv. pp. 17, 24, 64, 1880. 
3 Studier over Dekapodernes Slaegtskabsforhold, Dansk. Vidensk. Selsk. Skriv. (6te R.), Bd. i., ii., pp. 141, 159, 
200, 202, 1880. 
4 On the classification of the Maioid Crustacea or Oxyrhyncha, Journ. Linn. Soc. Lond. (Zool.), vol. xiv. pp. 634- 
673, pi. xii.-xiii., 1879. 
6 Etudes Zoologiques sur les Canceriens, Nouv. Archiv. Mus. Hist. Nat., i. pp. 177-308, pis. xi.-xix., 1865. 
6 Etudes Zoologiques sur les Crustaces recents de la famille des Portuniens, Archiv. Mus. Hist. Nat., x. pp. 309-428, 
pis. xxviii.-xxxviii., 1861. 
