1902.] NATURAL SCIENCES OF PHILADELPHIA. 535 



marked sexual difference in the coloratiou. Only sexually mature 

 individuals have been considered. 



It is very difficult to recognize the American species described 

 by C. Koch and "Walckenaer. I have examined Walckenaer's 

 descriptions very carefully, and believe that ^Yith the exception of a 

 very few forms, e.g., Lyeosa carolinensis, his species must be 

 regarded as unrecognizable. Walckenaer based his descriptions on 

 the manuscript notes and drawings of Bosc and Abbot; these 

 drawings have never been edited, and until they are published 

 they cannot rightly be granted any more priority rights than an 

 unpublished description, unless we should grant manuscript 

 drawings the value of type specimens. It would be as incorrect, 

 in face of the generally accepted rules of nomenclature, to name 

 species on the basis of unedited drawings as upon unedited descrip- 

 tions. Hence these drawings are of no decisive importance at all 

 until they are published, and Walckenaer's meagre verbal descrip- 

 tions comprise all we know of his species. Hentz's descriptions 

 are on the whole still less ample than Koch's and Walckenaer's, 

 but Hentz has given figures which, in the main, are good, so 

 that a considerable number of his species may be regarded as 

 recognizable. It is right to be very thorough in endeavoring to 

 recognize the species of a previous author, even when his descrip- 

 tions are very scant; but when the description is so inprecise as to 

 apply to any one of several species occurring in the locality of the 

 specimens described, then the specicis based upon such a description 

 must be considered unrecognizable and no further attention paid to 

 it. If this rule is not followed, our nomenclature would be based 

 upon a tissue of guesswork probabilities, and but for the date of 

 the tenth edition of the Sijstema Naturce, we should logically seek 

 in some earlj' source the names given by Adam. 



The works of the writers cited are arranged together in a list at 

 the end of the paper. 



Family LYOOSIDiE 



Characters oj the Family. — Araneoe with one pair of lung books 

 and unpaired trachsal spiracle ; with three claws on the feet, and 

 legs in-order of length generally 4, 1, 3, 2, or 4, 1, 2, 3; eyes4n 

 three rows, the first (most anterior) row of four small eyes, the 

 second and thiid each of two larger eyes. 



