10 [January, 



teriorem inermis. Pedes antici mediocres, carpo inerml, manu paulo tumida, 

 supra subgibbosa, digitis hiantibus, apice inflexis et acutis. Pedes 2di 3tii 

 4tique subaequi, tarsis fere rectis, longis, articulo penultimo longioribus. Hab. 

 in mari Atlantico juxta *' Rio Negro'' Patagoniae, et in mari Pacific prope 

 *' Valparaiso." Loiig. carapacis 3 4:'". 



Cyllene furciger. Rostrum elongatum, spiniforme, frontis latitudine non 

 brevior. Thorax infra ad extremitatem posteriorem duabus spinis longis diver- 

 gentibus postice productis armatus. Pedes antici angusti, carpo articuloque 

 secundo spina brevi curvatd armatis, brachio inermi. Tarsi 2di 3tii 4tique parce 

 armati, styliformes. Hab in mari Suluensi. 



Tribola lata. Carapax late ovatus non pubescens, paulo longior quam 

 latus, lateribus pone oculos parce undulatis, rostro lineari, dentibus frontis late- 

 ralibus rostro remotis, apice acutis et paulo divaricatis. Pedes antici parvuli, 

 tenues, manu pedibus sequentibus vix crassiore. Hab, in mari Atlantico, prope 

 insulas "Canary;*' e stomacho piscis " Bonito " lecta. Long, corporis fere \"* 



Tribola pctbescens. Carapax oblongus, subovatus, pubescens, lateribus pone 

 oculos undulalis, rostro lineari, dentibus frontis lateralibus rostro minus remotis. 

 Pedes toti dense brevissimeque pubescentes ; antici rostrum paulo superantes, 

 angusti, inaequi, manu dextra non latiore quam carpus. Pedes 8 sequentes fere 

 duplo longiores, 2di8 brevioribus quam 3tii. Hab. in Archipelago <'Paumotu " 

 mari Pacifico. 



Conspectus Crustaceorum^ ^c. Conspectus of the Crustacea of the Exploring 

 Expedition under Capt. C. Wilkes, U. S. N. By James D. Dana. 



MACROURA. 



We follow De Haan in placing the genus Galathaea with the Anomoura ; and 

 near it we arrange iEglea, which widely differs from most other related species 

 in having penicillate instead of foliose branchiae. 



The Macroura, excluding these groups, includes three distinct sections or sub- 

 tribes. 



One, the "Fossores " of authors, or the Thalassinidea, has close relations on 

 one side with the Paguri, and on the other with the Squillidae. They constitute 

 a line of gradation between these extremes, independent mostly of the other 

 Macroura, and osculating only with the Astaci, although removed from them in 

 general habit and structure. There is a diversity among the legs as to form and 

 position, which is not found in any other Macroura, and calls to mind the Paguri. 

 Moreover, there is in general a looseness of structure, a length of abdomen, and 

 sluggish habit of body, unlike the trim compact forms of the typical Macroura. 

 The anterior feet are thrown directly forward and are thus fitted for the burrow- 

 ing habits of the species. 



The second subtribe the Astacidea is composed of the highest grade of 

 Macroura, approaching in some points of structure the Brachyura. This is seen 

 in the fact that the sides of the carapax fold under and unite to the epistome, as 

 is well shown in Scyllarus and less perfectly in Astacus ; also in the absence or 

 small size of the basal scale of the outer antennae. The Astaci are the transition 

 species between the other Astacidea and the Caridea, and in the genus Parane- 

 pkropSf White, the antennary scale is not smaller than is common in the latter 

 group. Yet they properly form part of the same section with the Scyllari and 

 Palinuri, rather than a separate division as made by Milne Edwards; they differ 

 from all the Caridea in the transverse suture across the carapax near its middle. 



The third section the Caridea includes the typical Macroura, which have 

 the sides of the carapax not soldered to the epistome, and a large basal scale to 

 the outer antennae.* 



* The Cumae would constitute another section Cumidea if mature animals. But 

 according to recent researches of Prof. Agassiz, as he has informed the author, they 

 are in some cases, and probably in all, immature forms of Palaemon, Crangon, and 

 other known Macroural genera. 



