﻿122 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 102 



Uropod. — ^Dorsal branch with a single seta, ventral branch with four 

 setae on lateral margin and two apical setae. 



Types. — Holotype, allotype, and 15 female paratypes, collected at 

 the type locality, Marshalls, Tomales Bay, Marin County, Calif., in 

 shoreline plankton haul, October 31, 1947, by K. J. Menzies. Type 

 specimens have been deposited in the collections of the following 

 institutions : 



United States National Museum, holotype (No. 89520), allotype, 

 and 16 paratypes; Allan Hancock Foundation, 6 paratypes; Rijks- 

 museum van Natuurlijke Historie, Leiden, Holland, 3 paratypes; 

 Pacific Marine Station, 29 paratypes, accession numbers 1283-1290 

 Arth. 



Geographical distribution. — Seattle, Wash., to Tomales Bay, Marin 

 County, Calif. 



Material examined. — Specimens examined were collected from the 

 following localities : 



Washington : Seattle^ Carkeek Park, intertidal, on Polysiphonia. 



CALirORNiA : Sonoma County., Bodega Harbor, off Dusty's pier, No- 

 vember 29, 1947 (K. J. M.), 1 ovigerous female; Bodega Bay, whistle 

 buoy, 40 feet, July 14, 1948 (R. J. M.), 1 male. Marin County., 

 Dillon Beach, First Sled Road, January 21, 1948 (R. J. M.), 8 males, 

 13 females; Tomales Bluff, Tomales Point, bay side, August 18, 1947 

 (R. J. M.), 1 specimen; in tide-pool plankton haul, November 29, 1947 

 (R. J. M.), 3 specimens; Tomales Bay, Marshalls, shore-line plankton 

 haul, November 13, 1947, 11 specimens, mostly ovigerous females 

 (R. J. M.). 



Ecology. — This species appears to be one of the most abundant 

 species of intertidal marine isopods at localities near Dillon Beach, 

 and because of its apparent ability to thrive in vastly different ecologi- 

 cal conditions I have given it the name ubiquita. Specimens were 

 found on the Bryozoa Bugida paciiica and Tricellaria occidentalis and 

 in most tide pools and shore-line plankton hauls. The species appears 

 intertidally abundant in both protected bay and exposed rock-coast 

 localities. Specimens taken from Tomales Bay demonstrated a posi- 

 tive phototropism in the laboratory. Ovigerous specimens were 

 noted during January, October, and November. 



Remarks. — An examination of some paratypes of Munna acarina 

 Miller (1941, pp. 311-313, fig. 2) indicates that the species is closely 

 related to M. ubiquita. The specimens were kindly lent by Dr. Miller 

 from his personal collection. Munna nana Nordenstam (1933, pp. 

 222-225, figs. 56-57) similarly appears closely related to M. ubiquita; 

 however, in the paper cited Dr. Nordenstam makes no mention of the 

 species having 2-branched uropods. In a letter recently received 

 from Dr. Nordenstam he remarks that he has been unable to find a 

 dorsal uropodal branch on specimens of Munna nana. Munna ubi- 



