BEICHIOPOBA. 371 



interior ; whilst in several others there are but two hrachial 

 lobes. The Liassic species form the subject of a monograph by 

 M. Elides Deslongchamps ; they are often minute, and attached 

 in numbers to sea-urchins, corals, and terebratulse. 



Distrihutiorty 1 species. Mediterranean. 



Fossil, 34 species. Trias—. Europe. 



? Steingocephaltjs,, Defrance. 



Etymology, Strinx {stringos), an owl, cephale, the head.* 

 Type, S. Burtini, PI. XV., Fig. 13. Figs. 166, 167. Devonian, 

 Europe. 



Shell punctate ; sub-orbicular, with a prominent beak ; ventral 

 valve with a longitudinal septum (v s) in the middle ; hinge- 

 area distinct ; foramen large and angular in 

 the young shell, gradually surrounded by 

 the deltidium, and rendered small and oval 

 in the adult ; deltidium composed of three 

 elements ;; teeth prominent ; dorsal valve 

 depressed, cardinal process (/) very promi- rig. I67.t 



nent, sometimes touching the opposite valve, its extremity 

 forked to receive the ventral septum (v s) ; hinge-plate {p) sup- 

 porting a shelly loop, after the manner of Argiope. 



Family II. — Spieipehid^. 



Shell furnished internally with two calcareous spiral processes 

 {apophyses) directed outwards towards the sides of the shell, and 

 destined for the support of the oral arms, which must have 

 been fixed immovably; the spiral lamellae are sometimes 

 spinulose, indicating the existence of rigid cirri, especially on 

 the front of the whorls; valves articulated by teeth and 

 sockets. 



SpmiFEBA, Sowerby. 



Type, S. striata, Sby., Fig. 168. 



Synonyms, Trigonotreta. Konig. Choristites, Fischer. Del- 

 thyris, Dalman. Martinia, &c., M'Coy. 



middle ; the dotted lines proceeding from its inner edge are added from a drawing by 

 M. Suess, and represent what he regards as shelly processes for supporting a meiu- 

 branons disk. They may be portions of spirals, whose outer whorls are confluent. 



* Internal casts of Productus giganteus are called " owl-heads " by quarrymen in 

 the North of Eng and. (Sowerby.) 



t Fig. 167. Young shell, magnified four diameters; A, hinge area; b, deltiditim; 

 p, pseudo-deltidium. 



