REPORT ON THE CRUSTACEA MACRURA. 723 



The ophthalmopoda are short, thick, and borne on a short pedicle ; the ophthalmus 

 is produced to an obtuse point at the upper distal angle, which gives to the organ a 

 quadrate appearance ; hence the specific name. 



The first pair of antennae has the first joint of the peduncle a little longer than the 

 ophthalmopod and curved to afford room for the latter ; the second joint is less than 

 half the length of the first, and the third is about half the length of the second ; at 

 the extremity there are two slender flagella, but they are broken in the typical 

 specimen. 



The second pair of antennse carries a scaphocerite that has the margins parallel and 

 reaches as far as the distal extremity of the peduncle of the first pair. 



The first pair of pereiopoda (fig. Ik) is chelate and more robust than the second. 

 The second pair (fig. ll) is slender and chelate. The third and fourth pairs resemble each 

 other and are a little shorter than the preceding, whereas the fifth pair (fig. lo) is more 

 than twice their length and possesses a large, projecting, coxal joint. The entire limb 

 is as yet within its exuvium, and the extremity of the dactylos is broken off, but the 

 form of the inner or new structure appears rather to follow the lines of the exuvium than to 

 assume the form of the dactylos, shown in Diaphoropus versipellis (PI. CXVII. fig. So). 



The pleopoda are biramose and supported on a well-developed peduncle. 



The rhipidura is well developed and has the lateral plates subequal and reaching a 

 little beyond the extremity of the telson. 



Observations. — The second pair of pereiopoda is smaller than the first, but it exhibits 

 no sign of becoming multiarticulate, or the species might be thought to belong to 

 Parathanas. 



Bentheocaris. 1 n. gen. 



Carapace scarcely one-third the length of the entire animal, smooth, anteriorly pro- 

 duced to a short rostrum. Frontal margin without any very decided tooth. Pleon 

 having the five anterior somites subequal, the first two being rather the shorter, and the 

 sixth longer than any of the preceding. Telson long and tapering. 



Ophthalmopoda subequal with the rostrum, furnished with an ocellus mounted on a 

 tubercle. 



First pair of antennse biramose. 



Second pair supporting a scaphocerite of moderate proportions. 



Mandible supporting a two-jointed synaphipod. 



Second pair of gnathopoda long, slender, and pediform, and furnished with a 

 basecphysis. 



First pair of pereiopoda shorter than the second pah- of gnathopoda, and terminating 

 in a sharp point. Second pair of pereiopoda minutely chelate. Third pair long, slender, 



1 fSiv&QS) KCCQt's. 



