§ 278. THE CRUSTACEA. 829 
beneath which isa pair of strong upper jaws (Mondibulae), which move 
laterally by means of large muscles arising from the internal surface of the 
cephalic and dorsal parts of the skeleton; the internal border of these 
jaws is hard and often denticulated. With the higher Crustacea, these 
mandibles have a tactile organ (Palpus).® Behind these mandibles are 
two pairs of lower jaws (Mazillae), which are weaker, softer, and deficient in 
palpi. They are composed of several pieces, except with the Myriapoda, 
where they are fused into a kind of lower lip. Between the two mandi- 
bles and the first pair of maxiilae, there is a soft, tongue-shaped, and some- 
times bifid process, which, also, may be regarded as an under-lip. 
With many of the lower Crustacea, the parts about the mouth are vari- 
‘ously modified, whereby they lose their peculiarities as masticatory organs. 
‘Thus with the Poecilopoda, the mouth is simple, infundibuliform, and jaw- 
Jess, — the mandibles and maxillae being changed into cheliform legs. 
With the parasitic Crustacea, the organs of the mouth are changed into 
parts for Suction. The two lips are prolonged into a kind of proboscis, 
and the masticatory organs become more and more indistinct and finally 
disappear entirely. This is best observed with the Caligina where the 
mouth has the form of a beak pointing backwards, and the upper and lower 
lips are joined together forming a long tube which contains the two very 
long, horny, denticulated mandibles, while at its base are two palpiform, 
rudimentary maxillae. With Argzlus, the oral parts form a suctorial 
apparatus even more complete. This is a very long proboscis, pointing 
forwards, and out of which the two mandibles project in the form of two 
small pointed stylets, while the maxillae are entirely wanting.” With the 
Lernaeodea, and Penellina, on the other hand, the proboscis is short, and 
contains two short mandibles, which are denticulated and hooked; and on 
its outside are two palpiform, rudimentary maxillae.” But the oral parts 
are most abortive with the Ergasilina and Bopyrina. Here, the upper and 
under lips are blended together into a short proboscis without mandibles, 
3 With the Decapoda, Stomapoda, Amphipoda, 
and the majority of Isopoda. With the Chilopoda, 
these palpi exist only in a very rudimentary con- 
dition ; and they are entirely wanting with Idothea, 
the Chilognatha, and the other lower Crustacea. 
For the parts of the ‘mouth of Crustacea, see the 
descriptions and figures contained in the works of 
Savigny, Milne Edwards, and Erichson ; also 
the various monographic works upon the Deca- 
poda, Isopoda, Myriapoda, Phyllopoda, Lophyro- 
poda, and Cirripedia, by Suckow, Brandt, Rathké, 
Treviranus, Zaddach, Jurine, Lovén, Burmeis- 
ter, Martin St. Ange, &c. . 
4 Astacus, Palaemon, Palinurus, Squilia. 
« 
* [ § 278, note 7.] According to Dana, the pro- 
oscis here mentioned is simply a spicula without 
any mouth-opening or mandibular appendages ; 
the true mouth is posterior to this and has a trunk- 
form, with the buccal orifice on the under surface, 
as in some genera of the Caligoidea, and provided 
with regular mandibles; see Amer. Jour. of Sc. 
1837, XXXI. p. 299, also Rep. on Crust. loc. cit. 
p. 1322. This has since been verified by Vogt 
(Beitrage, &c., p. 7), and by Leydig: (loc. cit. Sie~ 
Dold and Kélliker’s Zeitsch. I. p.332, Taf. XIX. 
28% 
5 See Van der Hoeven, loc. cit. p. 16, Pl. II. fig. 
1, A. (Limulus). 
6 Milne Edwards, Sur Vorganisation de la 
bouche chez les Crustacés suceurs, in the Ann. d. 
Sc. Nat. XXVIII. 1833, p. 78, Pl. VIII. ; and espe- 
cially Burmeister, in the Nov. Act. Nat. Cur. 
XVII. p. 278, Tab. XXTII.-XXV. 
7 Jurine, loc. cit. p. 440, Pl. XXVI. fig. 3-7, 
16; Vogt, loc. cit. p. 7, fig. 5.* 
8 Nordmann, Microgr. Beitr. loc. cit. Taf. V.- 
IX., and Kollar, loc. cit. Taf. IX. X. (Actheres, 
Branchiella, Chondracanthus, Tracheliastes, 
and Basanistes) ; also Burmeister, loc. cit. p. 
310, Tab. XXIV. A. (Lernaeocera). 
fig. 2. b.). This last-mentioned author thinks that 
the spicula in question is a poison weapon ; a view 
which is rendered probable from the fact that it has 
glands connected with it, as in the stings of in- 
sects, which glands have hitherto been considered 
salivary ; but they do not open into the mouth like 
ordinary salivary glands, Moreover, Leydig 
quotes the observation of Jurine that tadpoles 
pierced by. this organ of Argudus, seemed poisoned 
and soon died. — Ep. 
