118 jficst annual Report 



STUDIES IN LACUNA ISOPODA 



BLANCHE E. STAFFORD 



In these and other studies, Asellus coiininniix has been used more 

 or less constantly as a basis of comparison, so that some drawings 

 (Figures 65 and 66) of this species are presented in this paper. All 

 of the other species were collected at Laguua Beach, California. 



The most robust and active Isopoda were found in the sand high 

 up on the beach where they were driven out by the incoming water 

 at high tide, and among the rocks at the high water mark. Of the 

 former, the sand Isopod, AUoinxcti* peri'<n/r< .1 -it*, was a common type, 

 and Lifji/tlti oci-idi'ittalix was the characteristic representative in the 

 latter surroundings. Under dead seaweed on the border of a salt 

 marsh two forms were collected in fair abundance, one of which, 

 Philnxciti richardsonae, lias been described in this report. At the 

 lower level, under the rocks which the low tide uncovered, various 

 forms of the family Idotheidn? were found; of these Irlotltra recti 

 lined was most numerous. Under these same rocks the species 

 C/ru/di/d iHirfnrtli was exceedingly plentiful. Hardly a rock was 

 turned over that did not abound in this form. 



Occasional specimens were brought in from holdfasts which had 

 drifted to shore from the kelp beds. These were generally very 

 minute forms. From the sponges many curious tube-dwelling Iso- 

 pods were collected. Rarely a parasitic form was discovered. The 

 tide-pools furnished interesting members of the family Janirida?. Of 

 most of the latter and of the rarer species drawings and descriptions 

 are not yet ready for publication. 



Asellus communis Say. 



Locality Fresh waters of Massachusetts. 



Body oblong and depressed, about three and a half times as long- 

 as wide, 17 mm. by 5 mm. 



Head measures 1.25 mm. in length and about 1 mm. in width at 

 upper margin and '2 mm. at posterior margin. Eyes small, composite, 

 and placed at the middle of lateral margins. First pair of antennae 

 have basal article of peduncle broader than those distal to it. Second 

 and third are narrow, third shorter than second; flagellum composed 

 of fifteen articles. Second antennae have a peduncle of six articles; 

 first very small, wider than long; second, third and fourth subequal ; 

 fifth and sixth long and narrower; sixth longer than fifth; flagellum 

 multi-articulate, composed of about sixty-two articles. Maxillipeds 



