100 THE VOYAGE OF H.M.S. CHALLENGEK. 



This species and that from Samboangan are doubtless the same, although the caudal 

 termination is rounded in the latter, and bifid in Phyllosoma philippinense ; the 

 basecphysis is absent from the third pair of pereiopoda. 



These two species, moreover, correspond closely with two taken off the Cape Verde 

 Islands, in the Atlantic, that are of the same size and of similar condition of development. 

 I am inclined to believe that both forms belong to the same genus as Phyllosoma furci- 

 caudatum, and this probably is generically related to some species belonging to the 

 Scyllaridse, and probably to the genus Ibaccus. 



Tribe Astacidea. 

 Family Ekyonida 



Cephalon dorsally depressed, having no rostrum. Lateral margin of the carapace hori- 

 zontally compressed and serrate ; broader than the pleon. Eyes wanting or abnormal ; 

 first pair of antennae supporting two multiarticulate flagella. Second pair having a 

 scaphocerite, and a long multiarticulate flagellum. Gnathopoda pediform. Pereiopoda 

 seven-jointed ; first three pairs chelate ; posterior pair reversed, chelate occasionally 

 in the female, smaller than preceding. Pleopoda, except the first and sixth pair, having 

 a stylamblys. Outer branch of sixth pair without a diaeresis. Telson tapering. 



Observations. — Professor Camil Heller in 1863 described in his " Crustaceen des 

 siidlichen Europa," under the name of Polycheles typhlops, a small Crustacean, of which 

 he only had a male specimen, found in the collection of the Museum at Vienna. It was 

 supposed to have been taken in the Mediterranean, somewhere near the island of Sicily. 



Its interest appears to have been much overlooked by naturalists, until Sir Wyville 

 Thomson published, in Nature, May 15, 1873, ten years after Camil Heller's description, 

 some notes by Dr. v. Willemoes-Suhm of the Challenger, upon a closely alli-ed form that 

 was dredged on the 4th of March preceding in the middle of the North Atlantic, at a 

 depth of 1900 fathoms or rather more than 2 miles from the surface. To this animal 

 the describer gave the name of Deidamia leptodactyla, the generic name of which was 

 afterwards withdrawn, because it was found to have been given previously by Dr. Clemens 

 to a genus of North American Lepidoptera, and the name Willcmossia, out of compliment 

 to the ill-fated naturalist of the Challenger, was given to it by Dr. Grote in 1873. 1 



The great depth from which it was dredged, a depth that was previously believed to 

 be barren, if not of all life, certainly of animals so high in the scale of existence, the 

 apparent absence of the power of vision, and the relationship of the animal to forms of 

 Crustacea that were supposed to have been extinct since the period of the Liassic Limestone 

 of England and the Upper White Jura of Bavaria, gave a considerable degree of interest 

 to the discovery. Shortly afterwards a second smaller species in shallower, but still 



1 Nature, vol. viii. p. 485. 



