REPORT ON THE CRUSTACEA MACRURA. 533 



chela, which breaks up into a brush of numerous, peculiar, thick, scaly hairs. The three 

 succeeding pairs of pereiopoda are moderately robust and terminate in a single unguis. 



The pleopoda are biramose, and the rhipidura well developed. 



This genus, if it be separate from Alpheus, rests its characters chiefly on the form of 

 the second pair of pereiopoda, which, instead of having the carpos long, multiarticulate, 

 and terminating in a small chela, has it short and only five-articulate, the propodos being 

 long, narrow, and gradually tapering to a point that is tipped with a brush of radiating 

 hairs. The. dactylos with the polliciform extremity forms an extremely small chela, 

 which is scarcely determinable under a magnifying power of sixty diameters, and the 

 fingers of which are broken up into and support numerous hairs. 



Cheirotlirix parvimanus, n. sp. (PL XCVI. fig. 2). 



Dorsal surface of the carapace continuous in the same horizontal line with the pleon. 

 Rostrum slightly elevated at the apex ; frontal margin of the orbital lobes produced to a 

 sharp point reaching nearly as far as the rostrum. 



Pleon having the somites anteriorly as deep as the carapace and gradually lessening 

 posteriori}-. 



The ophthalmopoda are short and entirely hidden beneath the carapace. 



The first pair of antennas has the first joint of the peduncle subequal with the length 

 of the rostrum, and carries a strong stylocerite that reaches beyond the extremity of the 

 first joint ; the second and third joints are short, and together subequal with the first, 

 the third supports two flagella, of which the principal one is the shorter and is furnished 

 with a thick mat of membranous cilia, and the other is equal in length to the carapace. 



The second pair of antennae is nearly as long as the animal and supports a scaphocerite 

 that is broad, ovate, and armed with a tooth on the outer margin. 



The first pair of gnathopoda has the distal joints reflexed, and the basisal carries a 

 long ecyphsis. 



The second pair is long and slender, carries a long basecphysis, and is tipped with 

 several small spinrdes. 



The first pereiopod on the left side has the propodos long and subcylindrical, the 

 pollex straight, slightly oblique, and tapering, and the dactylos longer than the pollex, 

 and at the extremity strongly curved and pointed. The second pair of pereiopoda is 

 short, having the carpos five-articulate, the propodos long and tapering, and at the 

 extremity tipped with a radiating bunch of hairs. 



The rest of the animal is like Alpheus, but since the first pereiopod has been lost 

 from the right side, there is no means of determining whether the pair be symmetrical, 

 as in Athanas, or asymmetrical, as in Alpheus. I am, therefore, induced to consider it 

 as a link between these two genera. 



