184 CRUSTACEA—EUCARIDA——DECAPODA CHAP. 
stock, and hence that the development of the Brachyura ran 
through an Anomurous strain; but Huxley, and latterly Bouvier,’ 
adopt the view that the Dromiacea are descended, not from the 
Galatheidae, but direct from the Macrura, and especially from 
the Nephropsidea. Special resemblances are found between the 
Jurassic Nephropsidae and certain present day Dromiacea, e.g. 
Homolodromia paradoaa, the detailed form of the carapace in the 
two cases being very similar. It is, however, a little strange 
that in the Dromiacea we meet with the same reduction and 
dorsal position of the last, or last two pairs of thoracic lmbs 
which we saw to be such a characteristic feature of the Anomura, 
especially of the Galatheidae. In the Dromiacea these limbs may 
be chelate, and they are used for attaching shells and other 
bodies temporarily to the back. Must we suppose that this 
resemblance to the Anomura is due to convergence, or that the 
Nephropsidae, which gave rise to perhaps both Galatheidae and 
Dromiacea, had this character, and that it has been subsequently 
lost in the Macruran stock? We have already mentioned that 
the Metazoaea of Dromia has not only a well-developed swim- 
ming third maxillipede, but also a biramous first pereiopod, a 
character which speaks strongly for Macruran affinities. 
Fam. 1. Dromiidae.—The eyes and antennules are retractile 
into orbits. The last two 
pairs of thoracic lmbs are 
small, and held dorsally. 
The sixth pair of pleopods 
are rudimentary or absent. 
Homolodromia from West 
Indies, deep-sea. Dromia, 
widely dispersed. D. vulgaris 
Fig, 126.—Dromia vulgaris, x 1. (After (Fig. 126) occurs on the 
Milne Edwards and Bouvier.) =e 
_ English coasts. 
Fam. 2. Dynomenidae—Similar to the preceding family, 
but only the last pair of thoracic limbs is small, and held dorsally. 
The sixth pair of pleopods are reduced, but always present. 
Dynomene in the Indo-Pacific. 
Fam. 3. Homolidae—The eyes and antennules are not 
retractile into orbits. Only the last pair of thoracic limbs are 
reduced, the sixth pair of pleopods altogether absent. Homola 
1 Loc. cit. p, 183. 
