à 
On the Classification of the Crustacea Choristopoda | 203 
attached to the front of the head, with the eaudal stylets free; the third 
(Spheromide) has ihe antenna attached. to the front of the head, with 
the inner lamina of the caudal stylets united to the abdomen. In 
the Cymothoidz, the legs are all ancoral and the caudal stylets and 
branchize are not ciliated ; ; in the /Egida and Spheromide, only the two 
or ihree anterior pairs of legs are ancoral, if uu and the caudal stylets 
and branchiz are commonly ciliated. A sing!'e genus of the Cymo- 
thoide (JEsathoa) has the habit of /Ega and ciliated caudal stylets, with 
the antenüs and ancora! legs of Cy mothoa. This cilation of the lam- 
ellar abdominal appendages appears to be a mark of degradation in the 
species, and is strikingly characteristic of the abdominal natatory feet 
of the Amphipoda. "l'he family A2gid&e contains two groups, distinct 
in babit; one (ZEgine) often parasitic, having the 6 anterior iegs an- 
coral, the other (Ciroíanine) not parasitic, and with none of the legs 
ancoral.] 
Fam.I. CYMOTHOIDA-.* 
Maxillipedes breves, 3-4-articulati, operculiformes, articulis termin- 
alibus angustis brevibus. Appendices caudales libere, marginibus ra- 
rissim8 ciliate.. Àntennz sub capite infixee. Abdomen 4-6-articulatum, 
segmentis anterioribus raro conpatis. Pedes toti ancorales.  Branchiee 
sepissime non ciliatzee. Epimerzs conspicus. 
Subfam.]1. CYMOTHOIN.JE.--Lameliée caudales nude. | Abdomen multiarticu- 
latum, segmentis liberis. 
G.1. Cvwornoa, Fabr. —EFemore lata, posteriora latissima. | Segmenta thoracis 2 
3ve postica multo breviora nunquam latere acuté producta. Segmentum. cau- 
dale. sapissimé valde transversum. Antenne graciles; 1m: ad basin paulo 
remote. 
G. 2. CrRATOTHOA,] Dana.—Cymothoc affinis, Antenne lm crasse basi con- 
juncte. | Caput postice latum, fronte productum et; sepe angustum. 
G. 3. Livoswxca, Leach. — Femora latiuscula, 6ta vel ma 5tis vix latiora, non an- 
gustiora. Segmenta thoracis 9tium 4tum 5tum 6tumque fere equa, 7mum 
paulo brevius Abdomen thorace subito vix angustius. Caput parvulum. 
Frons non involutus et in processum inter-antennalem conspicue non productus. 
Segmentum caudale vix transversum, | [Corpus sepe oblique distortum.] 
G.4. AxiLocRA, .Leach.—Femora angusta, posteriora angustiora. Segnientum 
thoracis 2dum 3tium 4tumve 5to 610 move multo brevius.' Abdomen thorace 
subito angustius, segmentis processu laterali spiniformi infra non | instructis, 
ultimo vix transverso. 
Subgen. 1l. AwrLocRA.—Rami appendicis csudalis multo inequi. 
Subgen. 2. OaxoriRA, .Leach.—hami appendicis caudalis subsequi. 
G. 5. Nznocrza, LLeach.— Femora et segmenta thoracis ac in Ziniloerd... Abdomen 
thorace subito angustius, segmentis processu laterali spiniformi infra instructis, 
ultimo vix transverso. 
G. 6. OrxcmaA, Leach.—Femora latitudine mediocria. , Segmenta thoracis 8 pos- 
tica. anterioribus non longiora. Abdomen thorace subito multo angustius, seg- 
mentis cum processubus spiniformibus infra non instructis, ultimo non transverso. 
 Subfam. 2; OROZEUKTINJE.—Segmentum abdominis postieum ac in Cymo- 
thoá ; segmenta alia coalita et non libera. 
G. 2. Ongozxuxkvzs, Edw. 
* Cwmothoadiens Parasites, Edw. — Crust., iii, 298, 9477. 
1 Cymothoa Gaudichaudii e& C. parallela hic pertinent. 
GOL SEM Ce E ME ELEM — EN GLEN EE d i 
