136 SPECIES OF THE SYSTEMA. 
fossil, which answers to the ‘ spinis longitudine teste,’ and has 
been figured by Walch (1768), Walcott (1799), and eventually 
as Terebratulites spinosus, by Schlotheim in 1813.” 
DEY TA Ta ie. 
Linneus, in his manuscript, has proposed the separation of 
certain of his species (viridis, bidens, &c.) under the name of 
Perna, which he has thus characterised :—‘‘ Dens terminalis, 
unus alterve insertus; margo lateralis fossula excavatus.” 
Though somewhat similar to the restricted Mytilus of modern 
writers, the genus would have been more confined, since our 
author did not include such as had granular denticles (edulis, 
for instance), or an apical plate (bilocularis). He was puzzled 
about hirundo, which he referred to his intended genus with a 
note of interrogation attached. 
Motilus evista-qallt. 
In the box thus marked in the Linnean cabinet is still pre- 
served the Ostrea crista-galli (Chemn. Conch. Cab. pl. 75, f. 
684) of authors. The excellent description in the ‘Museum 
Ulrice’ caused the early recognition of this peculiar-looking 
species. The reference to Sloane must be erased from the 
synonymy. 
Motilus hvotis. 
The description in the ‘Museum Ulrice,’ illustrated further 
by the figure of Rumphius (the engraving of Argenville does . 
