AIA GEOLOGICAL SURVEY OF THE TERRITORIES. 
The nomenclature and synonymy of the parts of the Crustacean limb: 
in general may, then, be tabulated as follows: 
Epipodite, flabellum, scaphognathite, gill-scraper, a ‘an. (In Limnadia 
Epipodal portion of limb - + upper or dorsal (br) part (oviger) ana lower (br). 
ranchia, 
eee in Phyllopod thoracic legs. 
3 endites in 2d maxilla of Astacus and Sergestes. 
4 endites in Ist maxillipede of Astacus and Sergestes. 
2endites (5th and 6th endopodite and exopodite) in 3d mazxilli- 
pede of Astacus and Homarus. 
1 endite ? (=5thPhyllopod endite?) in thoracic leg of Homarus and 
Astacus arising from a2-jointed axis or protopodite (consisting 
of coxopodite and basipodite), to which are appended 
(a) epipodite and branchia. 
(5 dactylopodite. 
(b) (endless) the leg in Decapoda with 5 . é Dee i 
joints | 2 meropodite. 
(1 ischiopodite. 
The carapace.—This is seen, when we study the development of the 
Phyllopods, to originate in the Nauplius as the undifferentiated covering 
or tergal portions of the first and second and mandibular segments of 
the Nauplius, which become enlarged during the successive moults 
of the animal until, as in Hstheria or Limnadia', it may cover the 
entire body. In adult life it becomes bivalvular and is attached to 
the body by the adductor muscle, which is situated in the mandibular 
segment, the prz-oral part of the head in the Limnadiade and Apodide 
being more or less differentiated from the carapace proper. 
As long ago pointed out by Professor Dana, the carapace of the De- 
capoda (the lobster for example) is a development of the tergal portion 
of the second antennal and mandibular segments. The development 
of Penewus and Huphausia from the nauplius to the adult confirms the 
view that the carapace is originally the antennal and mandibular tergites 
which form a single carapace and finally covers the cephalothorax of 
Decapoda. That no part of the carapace represents the thorax is 
seen in the zoéal carapace which covers the front part of the body OEE EG 
the thoracic segments are developed. 
Endopodal portion of limb, with— 
l 
HOMOLOGY OF THE EYES. 
When we consider the nature of the compound eye of the Cladocera 
and Phyllopoda and study the mode of development of the cornea from 
epidermal cells, we see that the eye-stalk of the Branchipod eye is 
simply an unjointed protuberance of the first antennal segment, and 
can in no way be regarded as the homologue of a jointed appendage. 
Moreover, the embryology of these Crustacea shows that the compound 
eyes are developed upon the tergal part of the first segment of the head, 
and that there are no traces of a pre-antennal segment. 
In the Decapoda our unpublished observations on various zoe (Lupa, 
Palemon and Tozeuma carolinensis), as well as the data given by those 
who have written on the embryology and metamorphosis of Decapods, 
all show that the faceted stalked eyes of Decapods should not be re- 
garded as homologues of the legs, although eminent authorities, such 
as Huxley, Claus and others, regard them as being the morphological 
equivalent of the succeeding jointed members. In Tetradecapods the 
compound eyes are invariably sessile. In the Merostomata, Limulus, as 
1In Limnadia, as shown by Lereboullet (see Fig. 43), and in Estheria, as stated by 
Claus, the carapace valves apparently arise from a post-mandibular segment, but this 
is exceptional among the Phyllopods. . 
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