146 DR BAIRD ON ENTOMOSTRACA. 



Legwn 3d, — Cirrhipoda. 

 Mouth possessing organs of mastication, consisting of lateral 

 jaws. Feet numerous, in pairs, consisting of many small ciliated 

 articulations. Body enclosed in a hard testaceous covering, com- 

 posed of several pieces. Fixed to rocks or to other marine sub- 

 stances. 



BRANCHIOPODA. 



Order 1.— PHYLLOPODA— Latreille. 



Feet numerous, generally at least twenty in number, and some- 

 times many more. Articulations foliaceous and branchiform, be- 

 ing chiefly adapted for respiration, and not for locomotion. Eyes 

 generally two, but sometimes three ; in some situated at the ex- 

 tremity of two moveable peduncles. Antennae generally of only 

 one pair, though sometimes two, — in most, small and not fitted 

 for assisting the animal in swimming. Mandibles always without 

 palpi. 



FAMILY 1.— APUSID^. 



Antennae, one pair, short and styliform. Eyes, three. Feet, 

 sixty pairs. Nearly the whole body covered by a large shield- 

 formed carapace. Body composed of numerous rings. 



Genus 1st. — Apus, ScJujeffer* There being only one genus in 

 this family, the characters given above will apply to the genus. 



Sp. 1st. — Apus cancriformis, Latr. Monoculus apus, Linn. 

 Branchipus cancriformis, Sc}uBffer.\ Limulus cancriformis, Lamk, 

 Binoculus cancriformis, Leach. 



Sp. 2d. — Apus Montagui, Leach. Encyc. Brit. Suppl., t. 1. 



FAMILY 2.— NEBALID^. 



Antennae, two pairs, large and ramiform. Eyes two, peduncu- 

 lated. Feet, twelve pairs ; eight branchial and four natatory. 

 Carapace enclosing head, thorax, and part of abdomen, almost in 

 form of a bivalve shell. 



Genus 1st. — ^Nebalia, Leach.X There is only one genus in 

 the family. 



Sp. 1st. — Nebalia Montagui, Thompson.^ Monoculus rostra- 



tus, Montague. 



* Monogr., tab. 1 — 5. f Element. Entomol., t. 29, p. 1 — 2. 



X Zool. Miscell., I. § Zool. Research. 



