162 



nitidissima, semiglobosa, ad basim ovata, sulcis profundis creber- 

 rimis radiantibus acutis insculpta ; apice terminali, acuto, vix 

 curvato, submarginali : subtus ad marginem antice acuminata, 

 postice septiformis. Long. ^, lat. f , alt. ^ poll. Hab. Feejee 

 Islands. 



The beautiful crystalline, quartz-like lustre of this shell, its 

 deep, regular sulci, and its crepiduloid base very distinctly mark 

 this species. 



A communication from C. G. Forshey, Esq., concerning 

 the appearance of the Locust, Cicada septemdecim, in 

 Louisiana, in 1835, was read. 



Mr. Forshey gives in the main an account of the animal, very 

 similar to that given by others. He states, hov/ever, that the 

 number of ova deposited in one nidus is uniformly sixteen. The 

 insect appeared to prefer the oak, small twigs of which being 

 selected, the ovipositor was thrust into the medulla and killed it ; 

 the eggs were then deposited, two by two, symmetrically, in the 

 ligneous fibres, on each side of the medulla. Three nidi are 

 usually found in the same twig. The branches thus pierced, all 

 die and drop off, and the larvae pass from the eggs into the 

 ground. 



The singing apparatus of the male is described as situated on 

 each side of the base of the abdomen, where two cartilages or 

 lids cover two cells or cavities, bounded internally by delicate 

 elastic tympana or timbals of triangular form, which are caused 

 to vibrate by a sudden muscular contraction and expansion. The 

 sound is one of sadness, as heard in the deep woods, according 

 well with the superstition that the W marked on their wings is a 

 harbinger of war. Some persons have been so fanciful as to 

 find VV on one wing, and by inversion M on the other, which is 

 supposed to indicate war with Mexico. 



The Mississippi appeared to be a boundary to their progress in 

 that neighborhood, as none had been noticed west of the river. 

 Neither had they appeared anywhere in the alluvial lands, which 

 fact, the writer suggested, was probably owing to their inability 

 to survive the long continued inundations to which these lands are 

 occasionally subjected. 



