RETORT ON THE CRUSTACEA MACRURA. 



591 



" Fig. 4. — d. Rostrum straight ; apex broadly truncated, directed forwards, quadri- 

 dentate, apical teeth very minute ; below, two teeth ; proportion, 2 per cent. 



" Fig. 6. — e. Rostrum straight ; apex acuminate, simple, directed upwards ; rostrum 

 with two teeth below ; one specimen out of 300 examined. 



"Fig. 5. — -f. Rostrum straight; apex bifid; rostrum with three teeth below, viz., 

 one beneath apex and two closely approximated in the broadest portion of the rostrum ; 

 one specimen. 



" All these specimens in addition have the basal superior tooth (characteristic of the 

 species). Another curious form had the rostrum very much curved upwards, apex 

 simple, and teeth below absent. These all were from the same pools, — in company 

 with Mysis chameleon, Carcinus mamas, Cancer pagurus, and that strange Edrioph- 

 thalmous Crustacea Apseudes talpa." 1 



Hippolyte bidentatus, n. sp. (PI. CV. figs. 1, 2). 



Carapace smooth, having the dorsal surface level with the rostrum, which is more 

 than half the length of the carapace ; upper margin armed with a small tooth, halfway 

 between the orbital margin and the apex of the rostrum ; the lower margin with a 

 simdar tooth a little in advance of that on the upper surface. Supraorbital tooth well 

 developed. Pleon slightly curved at the extremity of the third somite, which is 

 produced posteriorly in the median line; the fourth somite is dorsally smooth; the fifth 

 is armed on the posterior margin with two sharp teeth, one on each side of the median 

 line ; sixth somite unarmed. Telson long, narrow, tapering, extremity truncate and 

 furnished with a small spine at each angle, and another more important on its inner 

 side. 



The ophthalmopoda are about half the length of the rostrum. 



First pair of antennas only slightly longer than the rostrum. 



Second pah' having the scaphocerite subecpaal in length with the rostrum, and a 

 flagellum that is about the length of the animal. 



First pair of pereiopoda short and robust. Second pair a little longer than the 

 preceding and more slender. Third, fourth, and fifth pairs longer than the first two, 

 robust, and terminating in a strong unguis flanked on the inner side by numerous 

 spinules. 



