16 U.S. NATIONAL MUSEUM BULLETIN 29 5 



Masticatory processes of maxilla long and slender with 2-6 setae, 

 each of differentiated size and structure, posteroventral platelet 

 bearing 6 heavily chitinized unfeathered setae. Vibratory plate of 

 first thoracic leg triangular, with 4 unfeathered ventral setae and 

 many feathered setae; basal podomeres of second and third thoracic 

 legs with two ventral setae; all legs pediform. Furca with 6 or 7 setae, 

 seta 2 twice as long as others and feathered. Male brush-shaped organ 

 asymmetrical. Copulatory organ large, pigmented, with hemioval 

 median segment, smaller distal segment, arched copulatory tube; 

 genital lobe with doubly coiled spiral tube. Distal portions of append- 

 ages and genitalia, carapace selvage, exterior setae, and sometimes 

 part of epidermis pigmented, dark brown to black. 



Remarks. — The appendage and genital anatomy of the Bairdiinae 

 are both complex and remarkably consistent. I would estimate at least 

 300 characters to be observable that are capable of some degree of 

 variation, but for mere distinction of species or genera less than 10 

 characters are necessary. Indeed, the copulatory organ alone will 

 sometimes be all that is necessary to identify a male to species. 

 Identification of a female (ignoring the carapace) is more difficult and 

 requires comparison of minute differences on very many structures. 

 Unfortunately, most published illustrations are not sufficiently 

 accurate for detailed comparisons. 



For a few of the species described here the entire anatomy is illus- 

 trated, both to demonstrate the general consistency of structure 

 from species to species, and to provide a sampling of the variation 

 possible in structures not usually considered to be diagnostic. That 

 such taxonomically controlled variation exists, for example, in the 

 maxilla (generally considered the most conservative of appendages 

 and rarely illustrated) may be seen in the comparison of Figures 6a, 

 I5e,f, ISd, 22a, 25d, 32a, 346, 38a, S9g, and 40/ It would seem that 

 the number, length, thickness, shape, pectination, barbs, etc., of indi- 

 vidual setae on the masticatory processes are capable of sufficient vari- 

 ations and combinations that each species has its own "fingerprint." 

 The usefulness of such a character, however, is severely limited by 

 the small size and difficulty of separating individual setae within 

 these bundles. 



Neonesidea, new genus 



Type-species. — Triebelina schulzi Hartmann, 1962, p. 44. 

 Etymology. — Greek neos, new +Nesidea Costa. 

 Diagnosis. — Carapace streamHned ovate and smooth, muscle-scar 

 pattern with 8 elongate scars arranged in three horizontal or diagonal 



