A New Species of Spirontocaris 133 



A NEW SPECIES OF SPIRONTOCARIS WITH NOTES ON OTHER 

 SPECIES FROM THE ATLANTIC COAST. 



By a. H. Leim, B.A., 

 University of Toronto. 



A study of the group of shrimps contained in this genus has been 

 undertaken to determine the systematic relationships of the species, and 

 it has seemed desirable to publish, as a preliminary report, a description 

 of one new species together with some notes on other Atlantic species. 

 These notes are in part records of hitherto unpublished variations and 

 in part an extension of published ones. 



I wish to express my indebtedness to Prof. A. G. Huntsman not only 

 for an introduction to the subject and the provision of the major portion 

 of the material, but also for much direction and assistance. 



Spirontocaris zebra, sp. nov., PI. II, figs. 1-4; PI. HI, fig. 5-9. 



Rostrum rather short reaching the distal end of the first protopodite 

 of the antennule in three of the specimens examined, and to the middle of 

 the first protopodite in the other two. In three cases there are three 

 dorsal rostral spines and in the other two there are two dorsal spines. 

 In all five specimens there is only one ventral spine. The rostrum ends 

 anteriorly in a spine which points slightly downward. The anterior 

 rostral spine is smaller than the others and is somewhat closer to the 

 second dorsal spine than it is to the anterior extremity of the rostrum. 

 In the specimens where there are three dorsal spines the posterior two 

 are equal in size and their distance apart equals the distance from the 

 anterior extremity of the rostrum to the second dorsal rostral spine. 

 The ventral spine is on the ventro-anterior edge of the rostrum and it 

 equals the posterior dorsal spines in size and is situated just anterior 

 and ventral to the first or anterior dorsal spine. Just ventral to the tip 

 of the second dorsal spine there is a slight angle in the ventral surface 

 of the rostrum due to the axis of the anterior part of the rostrum rotating 

 downward from the horizontal. The orbit is slightly behind the posterior 

 dorsal rostral spine. The dorsal surface of the carapace is highest about 

 one-third its length from the anterior end or at the point where the 

 second dorsal spine of the carapace is situated. It is about equal in size 

 to the second dorsal rostral spine and points forward. Halfway between 



