NEW MARINE ISOPODS' — MENZIES 117 



blunt apex. Ventral surface of cephalon posterior to oral area cov- 

 ered with conspicuous large scales. 



Peraeon. — First five somites similar in size. Sixth somite shorter 

 than fifth. Seventh somite one-seventh the length of sixth somite 

 and having only a crescentic dorsal area visible in dorsal view behind 

 the sixth somite. Second and third somites with an anterior dorsal 

 concavity for the reception of the posterior borders of the first and 

 second somites respectively. 



Pleon. — Demarcation of somites visible dorsally. First four so- 

 mites similar, the first slightly longer than the others. Fifth somite 

 about four times the length of fourth. Sixth somite firmly fused 

 with telson, having a dorsal median posterior concavity indicating the 

 line of fusion. Telson spatulate, apex evenly convex with a finely 

 crenulate margin, lateral borders smooth. 



First antenna. — Peduncle composed of four segments; fourth seg- 

 ment very small, only partially separated from third. Flagellum in 

 adult male composed of a large basal joint followed by a brushlike 

 series of five wide joints; in juvenile male, flagellum composed of a 

 single large ovoid joint; in female, flagellum consists of an elongate 

 basal joint having one or two minute joints at tip. 



Second antenna. — Peduncle composed of six joints. Flagellum 

 consisting of a single setiferous joint, which is about one-fourth the 

 length of the sixth peduncular joint and considerably narrower than 

 that joint. 



Max'dliped. — Composed of a large free joint which possibly pos- 

 sesses a minute terminal joint. 



First maxilla. — Outer lobe with about 12 marginal sawlike teeth. 



Mandible. — Reduced, partially fused with cephalon. Palp, lacina, 

 incisor, and molar process lacking. A thin transparent knifelike lobe 

 is present on inner margin. 



Peraeopods. — See figure 15, h-d. Gntithopod similar to that 

 figured for Paranthura elegans except that the striated membranous 

 lobe of the inferior propodal margin is lacking and the setal armature 

 is different. Inferior propodal margin of second peraeopod with 

 six 2-pointed setae. 



Uropod. — Endopodite scarcely exceeding telson length. Exopodite 

 narrow, with posterolateral margin not sinuate, apex pointed. 



Second male pleopod. — Apex of stjdus with a swollen nonsetiferous 

 lobe. 



Types. — Holotype, allotype, and 6 male, 6 female, and 2 juvenile 

 paratypes collected at the type locality, Tomales Bluff (bay side), 

 Tomales Point, Marin County, Calif., May 23, 1948, by R. J. Menzies; 

 washed with formalin from the holdfast of the alga Macrocysti-s. 

 Type material has been deposited as follows : 



