ZOOLOGY. 593 



large claws or forcipes, and furnished with setae or lamelli- 

 form branchiae ; eyes sessile, 



Fain. 1. Pholadoid, Mussel- Insects. 



Small, almost microscopical, and slightly annulated 

 animals with an uni- or bi-valvular dorsal shield or testa, 

 stunted maxillae, and few legs, having attached to them 

 setiform branchiae. 



These animals are found in all stagnant waters, in 

 which they are incessantly paddling or rowing them- 

 selves about. They remind us of those Infusoria which, like 

 Brachionus, are covered by a scute or shield. They 

 are what have been called Monoculi (Entomostraca or 

 Lophyropoda), e. g. Daphniae. 



Number of feet small, and beyond their appended setae 

 there are no branchiae ; two eyes frequently blended to- 

 gether ; antennae mostly furcate like the feet ; sexes sepa- 

 rate ; a perfect circulation within a true Mussel- like 

 ventral cavity. They are microscopic Mussels with eyes 

 and feet. 



Fam. 2. Tellinoid, Branchiopoda. 



Similar animalcules to the above, but with a body 

 strongly annulated, naked or covered with a double shell, 

 and provided with numerous feet, unto which are attached 

 leaflets that serve as branchiae. 



Here belong the Branchiopoda properly so called. 



Fam. 3. Cardiaceoid, Shield- Crabs. 



Large animals, with strongly annulated body and 

 numerous feet; head and back covered by a shield, 

 whereupon are the eyes Phyllopoda. 



Here range the Trilobites, Apus, and the Molucca or 

 King-Crabs. 



Order 2. Spaliinusclielartige> Sc/ieerenkrebse^ 



3510. Five pairs of thoracic feet, of which the first 

 pair is mostly large and forcipiform; the eyes upon 

 moveable pedicles or foot-stalks. 



These animals usually attain a striking size, and are 

 generally the largest among the horny Ancyliozoa. 



The sexual parts open mostlv upon the posterior legs. 



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