6 BRACHIOPODA. 



In 1842 Dr. Gray (Synopsis Brit. Mus. 1842, 88) proposed 

 the following division for the class Brachiopoda : — 



" Some are attached by means of a tendinous cord, which 

 passes out between or in a groove in one of the valves. The 

 family of Lingulidce are attached by a tendinous tube, resembling 

 the stem of the Barnacles, which projects between the apices of 

 the gaping valves, as in Lingula. 



" The family of Terebratulidce are regular and somewhat 

 like a Grecian lamp in form, and have therefore been caUed 

 Lamp-shells. The valves are articulated together, and the 

 animals are attached by means of a tendinous band, which passes 

 out of the hole in the apex of the upper valve, as in the Tere- 

 bratulae and Spirifer. 



" The family Discinidce, on the other hand, have the tendon 

 passing out of a hnear slit near the middle of the under valve ; 

 the shell is suborbicular, and the upper valve conical, like a 

 Patella, but more symmetrical — Discina. 



" Others are immediately attached by the outer siirface of 

 their under shell. 



" The family of Craniada are attached by their flat lower 

 valve, which has an obhque facet on the upper side ; the upper 

 valve is suborbicular, conical, with a subcentral apex like the 

 Discina : the muscular scars of the lower valves bear some re- 

 semblance to a face, hence the name of Crania. 



" The family of Thecideidee are fossil shells, very like the last, 

 but only attached by the apex of the lower valves, which is pro- 

 duced and somewhat lamp-hke, and the cavity is furnished with 

 a comphcated apparatus to support the internal organs, as in 

 TerehratulidcE — Thecidea. 



" The family of ProductidcB are fossils, probably alhed to the 

 latter ; one valve is concave, the other flat, or concave and pressed 

 into the cavity of the other ; the hinge-line is straight and the 

 shell subsymmetrical — Productus, Calceola." 



In 1846 Mr, W. King (Ann. Sf Mag. N. H. xviii. 1846, p. 28) 

 divided the genera of Palliobranchiata into the following fami- 

 lies : — 



1. Obolidce. 1. Obolus. 



2. LinguUdcE. 1. Lingula. 



3. OrbiculidcE. 1. Orbicula. 



4. CraniidcE. 1. Crania. 2. Siphonotreta. 



5. CalceolidcB. 1. Calceola. 



6. Strophomenids. 1. Strophomena. 2. Orthis. 3. Lep- 

 tsena. 4. Chonetes. 



7. ProductidcB. 1. Productus. 2. Strophalosia. 



