DESCRIPTIONS OF A NEW GENUS OF ISOPODA BELONG- 

 ING TO THE FAMILY TANAID.E AND OF A NEW SPECIES 

 OF TANAIS, BOTH FROM MONTEREY BAY, CALIFORNIA. 



By Harriet Richardson, 



Collaborator, Division of Marine Invertebrates. 



About eight specimens of the two new species to be described were 

 collected at Monterey Bay, California, b}^ Mr. Harold Heath and sent 

 to the United States National Museum. One of these species repre- 

 sents a new genus, Pcmcolus, the diagnosis of which is given below. 



PANCOLUS, ne^A^ genus. 



Eyes present, distinct. First pair of antennae composed of three 

 articles. Second pair of antenna* composed of five articles. First 

 thoracic segment permanently united with the head to form a cara- 

 pace. The following six segments are free and distinctly separated. 

 The abdomen is composed of only three segments, two segments 

 anterior to the terminal segment. There are but two pairs of well- 

 developed pleopoda. The uropoda are single branched and consist of 

 a peduncle and a branch composed of a single article. The first pair 

 of legs are chelate. All the following six pairs are ambulatory. 



PANCOLUS CALIFORNIENSIS, new species. 



Body narrow, elongate, 5^ mm. long, and almost 1^ mm. wide. 



Head as wide as long, 1^ mm. : 1^ mm., with the anterior margin 

 somewhat triangular between the eyes, which are placed in the 

 extreme antero-lateral angles. The head anteriorly is about half as 

 wide as it is posteriorly. The first pair of antennie have the first 

 article large and robust, about half as wide as long; the second article 

 is half as long as the first; the third is a little shorter than the second 

 and terminates in a bunch of hairs. The second pair of antennte are 

 shorter than the first, reaching only to the end of the second article of 

 the first pair of antenna?. The first article is longest, l)eing three 

 times longer than the second; the third is about twice as long as the 

 second; the fourth i* more than one and a half times longer than the 

 second; the fifth is minute and terminates in a bunch of hairs. 



Proceedings U. S. National Museum, Vol. XXVIIl— No. 1400. 



367 



