60 GEOL. AND NAT. HIST. SURVEY OF MINNESOTA. 



two larger spines; the inner ramus is of moderate size. The inner ra- 

 mus of the outer leg is obsolescent. The accessory spine of the outer 

 ramus is near the middle of its segment. Length 1.0 mm. 



Marsh finds this form in Green lake and the Great Lakes; it may, 

 therefore, be expected in Lake Superior in Minnesota. 



* Diaptonius aslilandi Marsh. 



Plate VI, Figs. 4-6. 



Marsh '93. 



"A small pelagic species closely resembling D. sicilis Forbes. In 

 form it is slender, hardly to be distinguished from D. sicilis and D. 

 minulus. The first joint of the abdomen in the female is longer than 

 the remaining part of the abdomen, is dilated at the sides and bears 

 two minute lateral spines. The second and third joints are so closely 

 united that the abdomen appears two jointed. The furcal joints are 

 about twice as long as broad. The aoteanfe reach just beyond the 

 furca. The right antenna of the male is much swollen anterior to the 

 geniculating joint, and bears on the antepenultimate an appendage 

 slightly exceeding in length the penultimate joint. This appendage 

 may be blunt pointed or slightly enlarged at the extremity. The 

 fifth feet of the female are rather slender; the outer ramus is two- 

 jointed. The third joint is represented by two short spines. The 

 inner ramus is one-jointed, a little longer than the first joint of the 

 outer ramus, armed at the tip with two rather loDg spines. 



"The feet of the male are slender. The basal joint of the right foot 

 is about twice as long as that of the left. The first joint of the outer 

 ramus is a little wider than long. The second joint is wider at the 

 inner than the outer end; the lateral spiue is stout, curved, situated 

 near the inner end. The terminal hook is slender and falciform. The 

 inner ramus is slender, one-jointed, and about one-third longer than 

 the first joint of the outer ramus. The left foot extends a little beyond 

 the first joint of the outer ramus of the right. The second joint of the 

 outer ramus has three blunt spines upon its apex and is armed with 

 minute bristles within. The inner ramus is slender, one-jointed, and 

 reaches about half the length of the second joint of the outer ramus. 

 Length of female 0.97 mm.; of male 0.89 mm." 



This is a pelagic species found in Lake Superior and others of the 

 Great Lakes, and consequently occurs upon the shores of Minnesota. 



* Diaptonius sicilis Forbes. 



Plates V, Figs 1-7; XIII, Fig. 18. 



Herrick '83 and '84; De Gnerne and Richard '89; Forbes '91; Marsh '93. 



The discrepancies respecting this species as described by various 

 authors must be due to heterogenesis. It varies greatly in size and 

 armature of the feet. The form is slender and graceful and very like 



