270 Bulletin Vanderbilt Marine Museum, Vol. VII 



somite. On the very large specimens there are usually only two 

 spines here on the first somite, these forming a well-separated, 

 submedian pair, there being two pairs each on the anterior mar- 

 gin of the first carinae of the second and third somites, the outer 

 pair of spines of each being approximately in line with the pair 

 of the first somite and the inner pair submedian, between these. 



The first abdominal somite has a flat carina posteriorly ciliate 

 on the anterior margin which fits beneath the carapace and is 

 followed in the median area by a smooth, glossy area which bears 

 a single, submedian, transverse row of ten to twelve low gran- 

 ules, each of which is fringed with posterior-directed fine cilia ; 

 the posterior half of this somite is marked by four close-spaced, 

 elevated, transverse, flat carinae, each being fringed on the ante- 

 rior margin by fine cilia ; the first carina bearing also on the an- 

 terior margin a well-separated submedian pair of forward-di- 

 rected spines ; these carinae are slightly interrupted and curved 

 on the lateral portions, conforming to the contour of the epimeral 

 region. The epimera are narrowed to a subacute rounded cari- 

 nate margin and have the anterior margin bent upward, rimlike. 



The second somite is about as long in the median line as the 

 first, but with the epimera narrowed to an acuminate, triangulate 

 tooth ; this somite is similarly smooth anteriorly and transversely 

 carinate on the posterior, but bears four submedian spinules on 

 the anterior margin of the first carina, the outer pair being ap- 

 proximately in line with those of the first somite ; the inner pair 

 being subequally spaced between the outer pair. 



The third somite forms the hinder margin of the dorsal por- 

 tion of the abdomen and is about as long as the second, but with 

 the smooth anterior portion smaller and the elevated transversely 

 carinate portion longer; the first of the four carinae bear ante- 

 riorly four spinules in line with those of the preceding somite. 

 The epimera are narrowed to an acuminate triangle. 



The fourth somite is as long medially as the third, deflected, 

 with the entire surface paved by four transverse flat carinae, 

 each posteriorly finely ciliate; these carinae being interrupted 

 and forming an elegant design on the epimera which are trian- 

 gulate but less narrowed than those of the preceding somite. 



The fifth somite is a trifle longer than the fourth one, with 

 the epimera reduced, subacuminate ; the posterior margin trun- 

 cate above thie base of the telson and concave on either side above 



