108 



ANALYTICAL INDEX. 



ClIAl'TEK in.— continued. 



'Mytilvs voimionPBVs fDreissena polymorphaj , . page 66 



Considered of foreign origin, .... ib. 



Description of the species, . . . . . ib. 



Inactive — dwells in fresh water, .... ib. 



2. MODIOLA — 



Mj'tilacean tribe dismembered by modern authors, . . ib. 



Mytilus Modiolus — Linn. (Modiola modiolus) — The Horse Mussel, ib. 

 Largest of the race of mussels, .... ib. 



Description of the animal, . . . . . ib. 



Often overspread with corallines, . . . .67 



Modiola barbata — The Bearded Mussel, . . . ib. 



Smaller than the former, and considered by some a distinct species, ib. 

 Resembles the Modiola in everything, . . . .68 



Modiola discrepans — The Corded or Corduroy Mussel, 

 Doubtful whether this subject should be thus classed. 

 Shell a rude oval, eighteen lines by nine. 

 Surface striated, .... 



Species comparatively rare, .... 

 Plate XII. described, . . . . . 



ib. 

 ib. 

 ib. 

 ib. 

 ib. 

 65-68 



3. Anodon avonensis (A. cygneusj, 

 Shell and animal described. 



Plentiful in Lochend, .... 

 Plate XIII. described, 



4. Cycleas cornea. 



Shell globular, three-eighths of an inch in diameter, 

 Description of animal, supposed of ascidian nature. 

 Motions of the species, .... 

 Spawn in September, 

 Plentiful in Lochend, .... 



ib. 

 ib. 

 69 

 ib. 



ib. 

 ib. 

 ib. 

 ib. 

 ib. 

 70 



5. Tellina, 



Shell and animal described, 

 Motions vehement, 



6. Venus virginea (Tapes ptdlastra) , 

 Shell and animal described, . 



ib. 

 ib. 

 ib. 



71 



ib. 



