DESCRIPTION OF A NEW SPECIES OF THE ISOPOD GENUS 

 CASSIDINIDEA FHOM ^lEXICO. 



By Harriet Richardson, 



Collaborator, Division of Marine Invertebrates, United States National Museum. 



Two specimens, representing a new species of Cassidinidea , were 

 collected by Dr. Edward Palmer in 1910, at Maron Lagoon, Madre, 

 Mexico. They*were found in oysters taken from salt water. 



Family SPH/EROMID^. 



CASSIDINIDEA TUBERCULATA, new species. 



Body ovate, twice as long as wide, 2^ mm. by 5 mm. Surface 

 smooth except the abdomen, which is covered irregidarly with small 

 tubercles. Color wliite, with numerous arbores- 

 cent markings of black. 



Head wider than long, with the anterior mar- 

 gin widely rounded and produced in a small 

 median point. The eyes are small, round, com- 

 posite, and placed in the post-lateral angles. 

 The first antemise have the first and third arti- 

 cles of the peduncle about equal in length, the 

 second somewhat shorter than either of the oth- 

 ers. The flagellum is composed of four articles, 

 the last being tipped with hairs. The first an- 

 tennae extend just a little beyond the posterior 

 margin of the head. The second antemise have 

 a flagellum composed of eight articles, the first 

 being twice as long as the second and the last 

 three minute. The second antennae extend to 

 the middle of the first thoracic segment. 



The first segment of the thorax is a little longer 

 than the following six, which are subequal. The lateral margins of 

 the segments are straight. The epimera are not distinct on any of 

 the segments. 



The abdomen is composed of two segments, the first of which is 

 short and has siiture linos indicating other partly coalesced segments. 



Fig. 1.— CAS3IDD.TDEA TUBER- 

 CULATA. X 12. 



Proceedinqs U. S. National Museum, Vol. 42.— No. 1886. 



107 



