PLEISTOCENE F0.S8ILS, 261 



longitudinal section through the body of the worm, anil shows nothing 

 of its external characters, and tlie somites of the body are indicated 

 only by the tufts of brown bristles or setsu at intervals along the sides, 

 in the best specimen these are in tlie middle j)ortion of tlie body, from 

 a tenth to a twelfth of an inch apart. On the anterior segments they 

 are closer together, the body liaving apparently been contracted in that 

 part. Each foot, as indicated by the setiu — the soft parts having 

 entirely perished — seems to have had one strong spine and several 

 others, very fine and hair-like, in a separate bundle. Wlien disengaged 

 from the matrix (which can easily be dime by treating a small portion 

 with diluted acid) and examined microscopically, they seem to be 

 simple, nearly straight and pointed. Near what seems to be the ante- 

 rior extremity are obscure indications of one of the horny mandibles. 

 These characters, as far as they go, would indicate a cha'topod worm or 

 "sea centipede," and, of the species known to me on our coasts, they 

 resemble most closely that above named, which seems to be tlie ^. caeca 

 of Fabricius, and is a common and widely distributed species in the 

 North Atlantic and Arctic seas. 



PROVINCE ARTHROPODA. 

 C/rt^ss / V. — Crustacea. 



The most abundant species are bivalve Entomostraca, 



which occur in great numbers in the Leda clay, associated 



with Foraminifera. The species in my collection have 



been kindly determined by Mr, J. S. Brady, who enumerates 



the following: — 



Cythere MacChesneyi, nov. sp. 

 " Daicsoni (Brady). 

 " globulifera (Brady). 

 " Logani, nov. sp. 

 Cytheridea papulosa (Bosquet). 

 " punctillata (Brady). 

 " Sorbyana (Jones). 

 •* Mvlleri. 

 Cytherura Hobertsoni (Brady). 

 Cytheropteron complanatum, nov. sp. 



" inflatum (B., C, and R., MS.) 



** angulatum (B., C, and R., MS.) 



Eucythere argus. 



