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PROCEEDINGS OF THE NATIONAL MUSEUM 



as follows: dorsum black-brown, keels coral, venter and legs pale 

 yellow." 



Variation: The material I have examined is quite homogeneous 

 in structure, there being no perceptible geographic variation. Kanges 

 of from 42 to 49 mm. in the length of mature specimens and from 8 to 

 10 mm. in the width has been recorded. There is no sexual dimor- 

 phism in this respect. 



Synonymy: Pachydesmus dams was originally described without 

 illustration of the gonopods, and it eventually fell into a sort of obscur- 



FiGURE 3. — Geographic variation of average length in nine populations of Pachydesmus. 

 Known ranges are represented by the outlined areas; the enclosed figures indicate the 

 average length of the specimens of that form measured. 



ity owing to the difficulty of visualizing its generic attributes from a 

 brief verbal description. The types were collected at Creston, 

 Natchitoches Parish, in the upland hill region of western Louisiana, 

 and were placed in the collection of the Museum of Comparative 

 Zoology. 



Twenty-two years after the description of clarus, Leslie Hubricht 

 obtained a single male (virtually a topotype), at Kisatchi, also in 

 Natchitoches Parish, La. This male was sent to Dr. Chambcrlin 

 and became the type of Pachydesmus kisatchinsis. Several years 

 later, H. F. Loomis examined the material of clarus at Harvard and 

 recognized its identity with kisatchinsis, the synonymy being recorded 

 in a short note published in 1948. 



