1889.] NATURAL SCIENCES OF PHILADELPHIA. 129 



4. Lithobius lapidicla Meinert. 



Two specimens, male and female. Joints of antennae 26 ; ocelli 

 8 or 9, in three series; coxal pores male 2, 3,3,2, female 3, 4, 4, 3; 

 spines of first pair of legs, 0, 1, 1 ; of penultimate pair, 1, 3, 3, 1 ; 

 of anal pair, 1, 3, 2, 0; spines of female genitalia stout, claw very 

 distinctly tripartite, middle lobe not much longer ; length male 7 raIU ; 

 female 8 mm . 



It is very probable that these specimens are not identical with 

 L. lapidicola, a European species; but as they are rather mutilated, 

 I have hesitated to describe them as new. 



May 7. 

 The President, Dr. Joseph Leidy, in the chair. 



Fifty persons present. 



The following papers were presented for publication : 



" Catalogue of the Asteroidea and Ophiuroidea in the collection of 

 the Academy of Natural Sciences of Philadelphia," by J. E. Ives. 



" Provisional List of the Plants of the Bahama Islands," by John 

 Gardiner and L. J. K. Brace. 



The Proceedings of the Botanical Section having precedence the 

 following communications were made : — 



On the Use of the Bambusa Stem, in Incandescent Electric Light- 

 { n g m — Prof. Wm. P. Wilson stated that the ordinary exogenous 

 woods are not adapted to the construction of the filament for 

 want of a homogeneous structure. Such woods are made up of 

 wood-cells of varying lengths and shapes in combination with a 

 variety of ducts and vessels. 



The walls of the wood-cells may be more or less thickened, the 

 vessels and ducts may be larger or smaller, numerous or infrequent 

 according to the kind of wood examined. There are always enough of 

 these vessels and ducts combined with the wood-cells in any stem to 

 render the structure exceedingly heterogeneous. Most of these 

 cells and vessels have their longer diameter parallel with the 

 general direction of the stem. Groups of thin walled, prismatic 

 cells pass radially from the central portion of the stem to the cir- 

 cumference. These groups of cells are called medullary rays. It 

 is impossible to cut a filament from any of these woods and so cut 

 it that the medullary rays will not cross it many times at right 

 angles to the ducts and long cells. The character of the cells form- 

 ing these rays is so very different from the others in the filament, 

 both as to shape, direction, and thickness of the walls, that at the 

 10 



