26 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 57 



are attached on the anterior side long spines carrying numerous 

 smaller spines on the margin opposed to the main body of the 

 appendage (pi. 4, fig. 4). There is also in this specimen a broad 

 appendage of three joints attached to the outer posterior end of the 

 basal joint. The features described are partially illustrated on pi. 

 4, by figs. 1-4. Fig. 3 illustrates some of the long spines where 

 they are sufficiently separated to show the shorter secondary spines. 

 Another unusual variation is illustrated by fig. i. In the small 

 specimen illustrated by fig. 2, pi. 2, it looks as though there were two 

 jointed branches extending outward with small spines on their 

 anterior margins. A larger series of specimens will undoubtedly 

 enable us to interpret these chelate appendages more accurately but 

 with our present information it seems probable that in the complex 

 form represented by fig. i, pi. 4, provision was made for capturing 

 the numerous small phyllopod crustaceans and numerous annelids 

 with which the bottom and adjacent water were abundantly sup- 

 plied. It may be that the chelate, complex appendages were also 

 used in fighting and that there was a marked difference in those 

 belonging to the male and female. 



The fourth pair of appendages so far as known have a small basal 

 joint or gnathobase which has on its inner margin two strong spines, 

 the form and size as compared with the gnathobases on the third 

 and fifth pair of appendages is illustrated by fig. i, pi. 5. The joints 

 beyond the gnathobase are elongate and form a slender appendage 

 that extends out beyond the third and fifth appendages. The term- 

 inal joint has three small spines projecting from its outer end. 



Each of the fifth pair of appendages has a large basal joint or 

 gnathobase, the inner margin of which is provided with short, 

 strong spines. As far as can be determined from the material 

 available for study, there are three or four strong, broad joints 

 beyond the gnathobase, the outer of which are provided with fine 

 setae or branchial filaments. The gnathobase is well shown by fig. 

 I, pi. 5, and the filaments on the outer joints by figs. 2 and 3, pi. 2. 



Ventral appendages: Abdominal. — A number of specimens show 

 more or less of traces of abdominal appendages on the first nine 

 segments of the abdomen. None of these indicates the presence of 

 a jointed appendage in any way comparable with the appendages 

 of the cephalo-thorax, or the abdominal appendages of the trilobite. 

 The appendages appear to be formed of clusters of branchial fringes 

 attached to short lobes that are round or oval in outline and affixed 

 to the ventral surface on each side of the abdomen at the outer 



