154 PROCEEDINGS OF THE NATIONAL. ]VnJSEUM vol. loi 



2 females, 1 ovigeroiis; May 23, 1948 (R. J. M.), 1 male, 1 female; 

 Tomales Bluff, bay side, November 28, 1947 (R. J. M.), 1 male, 2 

 females; November 30, 1947 (R. J. M.), 1 male, 2 females; May 23, 

 1948 (R. J. M.), 4 males, 14 females, 3 ovigeroiis; Duxhury Reef^ 

 August 15, 1947 (R. J. M.), 1 male, Monterey County ^^: Carmel 

 Cove^ July 18, 1947 (T. R. Howell), 1 ovigerous female; Asilomar, 

 July 16, 1947, Cadet Hand, 1 ovigerous female ; Point Pinos, July 3, 

 1947 (W. Fox, V. House, and L. Kellen), 1 male, 1 female; Pescadero 

 Point, July 8, 1947 (D. P. Abbott), 1 male. Orange County ^2. 

 Newport Bay, November 15, 1933 (G. E. MacGinitie), on boat bottom, 

 1 male. 



Ecology. — Specimens were collected most frequently from the lowest 

 exposed areas (zone 4) of the exposed rocky coast localities. They 

 were foimd on the algal 'holdfasts Egregia, Laminaria, and Macro- 

 cystis; on the bryozoans Costazia costazi, Filicrisia sp., and Tricellana 

 occidentalis ; on the tunicates Amaroucium^ calif OTniicum and Synoi- 

 cmn sp., as well as on hydroids and barnacles and under rocks in the 

 intertidal zones 3 and 4. 



Remarks. — This species certainly appears to be closely related to 

 Jaeropsis lobata Richardson. It differs from /. lohata in having 

 stout spines on the lateral borders of the pleotelson, a fringe of scales 

 on the outer margin of the rostral process and similar scales on 

 certain joints of the antennae and peraeopods. At my request Dr. 

 Fenner A. Chace, Jr., curator of marine invertebrates, U. S. National 

 Museum, kindly examined the type of /. lohata to discern whether 

 the structures mentioned above were present. Dr. Chace writes, "The 

 type of that species, so far as I ani able to make out, lacks the spines 

 on the pleotelson and the fringed scales on the frontal lamina. Both 

 of these margins appear to be perfectly entire." 



There seems to exist a definite correlation between the amount of 

 dark pigment on the body and the number of spines on the pleotelson. 

 Albino specimens of /. dubia had seven spines on each side of the 

 pleotelson ; other specimens having pigments concentrated on the head 

 but few pigments elsewhere had five to six spines on either side of 

 the pleotelson. The var. paucispinis, described below, in which more 

 pigments are present, has from two to three spines on either side of 

 the pleotelson. Richardson's /. lohata, a species having more pigment 

 than any I have examined, lacks spines on the pleotelson lateral 

 borders. Although the correlation between the number of pleotelson 

 spines and the amount of body pigment might indicate that /. dubia 

 is not distinct from /. lobata, other differences as enumerated above 



" Specimens lent to writer by Dr. Franlc A. Pitellca, Zoology Department, University of 

 California. Paratypes donated to U. S. National Museum. 



" Specimen lent to writer by Dr. Fenner A. Chace, Jr., curator of marine Invertebrates, 

 U. S. National Museum. 



