TRANSACTIONS OF WAGNER 

 786 



TERTIARY FAUNA OF FLORIDA 



< Mytilus + Vohclla Scopoli, Intr. Hist. Nat., pp. 396-7, 1777 ; Modeer, K. vet. Acad. 



Handl., xiv., pp. 179, 181, 1793. 



< Mytulus + Pc7-na Retzius, Dissert., p. 20, 177S. 



^ Afytz/us Bo\ten, Mus. Bolt., p. 157, 179S ; Ed. ii., p. 110, 1819. 



< Myfichis Cuvier, Tabl. Elem., p. 423, 1798. 



= Mytihcs Lamarck, Prodr. Nour. Class. Coq., p. 88, 1799. Type M. cditlis L. ; Link, 



Beschr. Rostock Samml., p. 158, 1807. 

 ? Arcomytilus Agassiz, 1840. Type Mytihcs pcctinatiis Sby. (? = Septifcr Recluz, 1848). 



The name Mytiliis for the mussels is of very ancient date, and in adopt- 

 ing it for his heterogeneous genus Linne merely followed classical usage. If 

 we ascribe the genus to Linne we are obliged to seek the type by his method 

 of taking the most common species, and while this might be done under stress 

 of circumstances, it is better, if practicable, to follow the regular rule. 



The naturalists who followed Linne did not grasp the characters which 

 separate the groups of the Linnean Mytili, and after eliminating the fresh- 

 water species, they seemed to fall back on the dentiferous or edentulous char- 

 acter of the hinge in their divisions of the group. Thus Scopoli divided the 

 Linnean Mytilus into an edentulous group, for which he preserved the name 

 without citing any examples, and Volsella, which included species with one or 

 more teeth. It was by some misidentification, therefore, that Mytilus modiolus 

 was included in Scopoli's Volsella and defined as having one tooth. Modeer 

 followed Scopoli, and Retzius did the same, except that he proposed a genus 

 Perna for the forms Scopoli had named Volsella. Even Cuvier included both 

 Mytilus and Modiola in his Mytulus. 



The first author who seems to have had clear and what may be termed 

 modern views on the subject was Bolten, who divided his Mytilus into a 

 smooth and a sulcate group and excluded nearly all the species not Mytiloid, 

 as now understood. He did not name a type, but this deficiency was supplied 

 by Lamarck a year later. 



A consideration of these facts shows that the course of some writers who 

 would substitute Volsella or Perna for Modiolus Lamarck is unwarranted by 

 the history of these names. The quadrinomials of Poli {Callitriche -\- Calli- 

 trichodcruia, 1791) have no place in our nomenclature. The names which are 

 entitled to adoption are all comparatively modern. The curious twisted sub- 

 genus Stavelia Gray, which is usually placed with Mytilus, should be removed 

 to Modiolus. Mytilaster Monterosato has vermiculate sculpture. 



The Mytili occurring in the North American Tertiary are divisible by 

 their sculpture into two sections : 



