REPORT ON THE CRUSTACEA MACRURA. 597 



smaller ones near the apex. Frontal surfaces of the carapace furnished with two supra- 

 orbital teeth, a well-developed antennal tooth, and another at the fronto-lateral angle. 

 Pleon having the third somite dorsally arcuate and posteriorly produced over the fourth, 

 but not elevated into a tooth. 



The first account of this species was given under the name of Cancer spinus, in a 

 figure and description by Mr. Sowerby in the British Miscellany 1806 ; this was followed 

 by a short notice by Leach under the name of Alpheus spinus, in the Transactions of 

 the Linnean Society for 1815 (?), and in 1817 by a figure with the details enlarged but 

 with meagre description in his Malacostraca Podophthalma Britannica. 



A fuller description was given by Milne-Edwards, but even this leaves out some very 

 important points, so important that it appears to me to be impossible naturally to retain 

 this species in the same genus with Hippolyte varians, which Leach states to be the type 

 of Hippolyte. 



As the species appears to have a very large area of distribution, it is highly desirable 

 that we should have a clear idea of its form and anatomical details, inasmuch as it 

 appears to bear largely upon the specific value of other forms, more particularly since it 

 has erroneously been accepted as the type of the genus Hippolyte by Stimpson, 

 Kingsley, and other authors. 



Leach's figure 1 was from another and more perfect specimen, but was accompanied 

 by only a meagre description. The rostrum is drawn enlarged (PI. CVI. fig. 1), and 

 stands at the anterior extremity of a conspicuous carina that extends to the posterior 

 margin of the carapace ; on the dorsal crest, posterior to the orbit, are five large teeth, 

 anterior to which, commencing just above the orbital margin, and continuous on the 

 rostrum, is a series of twelve small teeth, of which those near the centre of the series are 

 the largest, and the most anterior terminates at a little distance behind the apex. The 

 apex forms a cylindrical sharp pointed tooth, that is produced posteriorly as a lateral 

 ridge on each side through the middle of the rostrum to the base, where it is strengthened 

 and supported by two teeth, one above the other, on the inner angle of the orbit. The 

 lower margin of the rostrum descends from the apex perpendicularly, and forms a 

 broad, compressed plate, the anterior edge of which is furnished with several minute 

 teeth and a larger one, and still more distantly with another separated from the rest, 

 behind which the margin ascends, apparently to afford space for the freer movement of 

 the ophthalmopoda. 



The ophthalmopoda are uniarticulate, short, and pyriform (PI. CVII. fig. a). 



The first pair of antennae is furnished with a broad and sharp pointed stylocerite, and 

 supports two short, unequal flagella, that reach but little beyond the rostrum. 



The second pair is furnished with a broad scaphocerite, armed on the outer distal 

 extremity with a strong tooth. 



1 Luc. cit. 



