744 



ARTHROPODA 



PHTLUM VII 



iilerlocked on the dorsal edge, biit are only in apposition on tlie ventral 

 edge, wliere tliey were undoubtedly capable of dehiscence for 

 the Protrusion of the appendages. This is tlie most primitive 

 geniis of the group. Ordovician to Devonian. 



Family 2. Turrilepadidae Clarke. 



Body with four to six vertical columns of triangulär plates, 

 two of the columns heing small, accessory and sometim.es much 

 modified in shape. Gaudal plate patelliform, axial. 



Fid. 1437. Turrilepas Woodw, {Plumulites 



Lepidocoieus mriei Clarke. Barr.) (Fig. 1438). Body elongate- 



ventral views. large triangulär overlapping scales, 



some of which are keeled in the 

 middle. Besides having concentric Striae, the surface may be 

 radially lined or punctated. Cambrian (?) to Upper Devonian. 

 Strohilepis Clarke. Composed of four columns of over- 

 lapping plates, two of which are of large and equal size. 

 Of the other two intervening columns, one consists of a 

 few very small plates, and the other is modified into a series 

 of grooved spines which appear to overlap one another at 

 their bases, and to lie opposite the column of small plates. 



Fig. 1438. 



Caudal extremity terminated by a circular 

 plate, against the sides of 

 column. Middle Devonian 



Turrilepas ivrightianus de 



. , . ^ Koninck. Silurian ; Dudley, 



COnical, axial England. A, Complete indi- 



plate, against_ the rides of which lies the first plate in each Ä entrged^a'fter' Wo" 



ward). 



Family 3. Lepadidae Darwin. (Goose Barnacles). 



Shell pedunculated, composed mainly of the paired terga and scuta, the unpaired 

 canna, and a variable numher of small calcareous plates, some of which Cover the 

 flexible peduncle; others take part in the capitulum. The calcareous plates are never 



Archaeolepas Zittel (Fig. 1439). Peduncle flattened, the two principal surfaces 



Fio. 143'.». 

 Archaeoiejjax rei/lru- 

 hu;heri (Opp.). Litliu- 

 graphic Stone ; Kel- 

 heiin, Bavaria. Vi- C', 

 Carina ; R, Rostrum ; 

 'S, Scutum ; T, Terguni. 



Fig. 1440. 

 A, Loricula laevissima Zitt 

 Senonian ; Dülmen, West- 

 phaha. Vi. B, C, Lorimla 

 •'j.VnocaDames. Cenomanian 

 Lifibanon. 



Fig. 1441. 



Scalpellum gallicum 

 Hebert. Upper Cretaee- 

 ous ; Meudon, near Paris. 

 '^/i (after Hebert). 



Vi aiKi 2/j. 

 andaLnut:^.:3Xe"ClX::^^ä:ior^ unpai./ea.„a, 



I 



