ORAPSUX& 



ORAPSID.C. 



always of the ordinary length, and terminated by elongated and 

 multiarticiiUte appendages which are Tory distinct. The external 

 antenna: here fill the gap which exinU between the front and the 

 inferior orbital border, and which forma a communication for the 

 antennary piU with the orbits. Their first joint is nearly always 

 abort, but rather Urge, and nearly entirely covered by the front 

 The three following joints and the terminal stem are very little 

 developed. The anterior border of the epistome is always placed on 

 the same line as the inferior border of the orbit, with which it is 

 continuous. The buocal frame is but little or not at all narrowed in 

 front, and the terminal stemlet of the external jaw-feet always spring* 

 from the middle of the anterior bonier, or from the external angle of 

 the preceding joint, and is never hidden below it The palp of these 

 jaw-feet presents nearly the same form as in the crabs ; it is large, and 

 terminated by a multiarticulate appendage bent back inwards under 

 the third joint of those members. The sternal plastron is not very 

 wide backwards, and gives insertion to the mtroniissive organs. The 

 disposition of the feet varies ; those of the first pair are in general 

 short, and those of the four last pairs are very much compressed ; 

 these last are sometimes natatory, a character which is not met with 

 in any other crustacean of this family. The abdomen is composed of 

 even joints, and its second articulation extends nearly always, in both 

 one and the other sex, as far as the origin of the posterior feet The 

 thoracic branch!* generally amount to seven on each side. The epimure 

 of the last thoracic ring is nearly as much developed as that of the 

 preceding ring, and concurs to form the vault of the flanks ; thus the 

 superior or epimerean cellule of this penultimate ring does not cover 

 the cellule which corresponds to the posterior foot, as ia the case in 

 the Oecarcinions. 



The greater numbers of the tribe, as far as the manners of the 

 crustaceans composing it are known, live on the shore, or ou the rocks 

 which border the coasts; they are very timorous, and run away with 

 much swiftness. 



M. Milne-Edwards, who gives the above definition and account of 

 the Orapsoidians, divides the tribe into seven genera, namely : 



Saarma (Say). Carapace quadrilateral, nearly equilateral generally, 

 and very much elevated in front ; fronto-orbital border occupying its 

 whole width ; lateral borders straight, and posterior border very long. 

 Front nearly always suddenly bent down, and its length very consider- 

 able, exceeding half of the transversal diameter of the carapace. 

 Eyes large and of moderate length; orbits inclining to oval, with 

 generally at their external angle a large gap, which is continued with 

 a horizontal gutter situated immediately below the lateral border of 

 the carapace, a character found in Macroplithalmvu, but which does 

 not exist in the majority of the Qrapsoidians ; lower border of the 

 orbit horizontal and directed forwards ; a very strong tooth is directed 

 towards the front from its internal part Antennary pita transversely 

 oval, and the space which separates them generally very large, Basi- 

 lary joint of the external antennae more or less cordiform, giving 

 insertion to the succeeding joint in a notch situated in the middle ol 

 its internal border; its width is considerable, although the front 

 exceeds it laterally. Epistome very short and projecting, like all the 

 surrounding parts ; it is continued with the interior orbitary border, 

 and below that border there is a horizontal gutter which terminates 

 at the angle of the buccal frame ; there are also other furrows under 

 the pterygostomian regions, the surface of which ia granulous or 

 reticulated ; it is generally divided into small squares of great regu- 

 larity, and this character alone would suffice to distinguish the greater 

 part of the species of Saarma from nearly all the other Catametopei 

 The disposition of the external jaw-feet is also very remarkable ; for 

 there is always a wide lozenge-shaped space between them, and their 

 third joint longer than it is wide, and longer than the second, is 

 rather oval, and but little or not at all truncated anteriorly. It is also 

 to be noted that there exists on the surface of this lamellar portioi 

 of the external jaw-feet a projecting line or crest which is carriet 

 obliquely from its external and posterior angle to its interior (anterior ? 

 and internal angle; this crest is generally furnished with hair, am 

 there is a deep furrow near its external border. The sternal plastron 

 is generally convex from behind forwards, and in the male the anterior 

 portion of the cavity which receives the abdomen is rounded and sur 

 rounded with a small border. The anterior feet of the male are 

 nearly always much longer than those of the second pair, and ter 

 minuted by a strong and convex hand. Sometimes it is the same with 

 the female. The feet of the second pair are shorter than those of tin 

 thin), and terminate, like all the succeeding feet, by a large roundot 

 irtyliform joint which is more or less distinctly canaliculated, generally 

 downy, and almost always completely devoid of spines. The seconc 

 ring of the abdoman is in general nearly linear, and the last is mud 

 more narrow at its base than -the penultimate ring, so that at tlii 

 point the abdomen is abruptly narrowed. In the female the last join 

 of the abdomen is very small, and in general lodged almost entire!, 

 in a notch of the preceding ring. 



The species of this genus are found upon the coasts of America, 

 Africa, and Asia. 



Mr. Say, who first separated these crustaceans under the generi 

 asm* Saarma, afterwards reunited them to Qrapnu ; but M. Milne 

 K.I wards, who has entered into the details of the construction o 

 /Swanno above given, in order to point out its distinctions, is of opinio 



lat it ought to be distinguished, and to be considered as constituting 

 ne type of a rather numerous genus, which the latter divide* iuto 

 lie following sections : 



A. Species whose carapace is at least as wide as it is long, and but 

 little or not at all narrowed posteriorly. 



a. Lateral borders of the carapace armed with two or three t.-. t'n 

 (comprising the external orbital angle). Body very thick, 

 especially before. 



5. tetrayona (Cancer tetragontu (?), Fabr. ; C. fatcicularii, Herbst ; 



.-yimU telragona, Olivier; Graptut Mrayona, Latreille). Length 

 28 lines. Locality, Indian Ocean. 



a a. Lateral borders presenting no tooth behind the angle of the 

 external orbit Body depressed. 



S. quailrata (Cancer quadratia, Fabr. ; Ocypodt plicala, Bosc.) 

 ^ength, 8 lines. Locality, the neighbourhood of Pondicherry. 



B. Species whose carapace in much longer than it is wide, and 

 strongly narrowed backward*. 



5. Pitonii (Arala plnima of Piso). Length, 8 lines. Locality, the 

 Antilles. M. Milne-Edwards says that Latreille bns confounded this 

 ipecics with b'raptui cntentaliu. M. Milne-Edwards is also of opinion 

 hat O. JftuarJii (Deamareat) and Cancer Hiipantu (Herbst) beloug to 

 ,bjs genus. 



Cycloyrapiiu (Milne-Edwards). Body much less flattened than in 

 Graptiu and wider, the transversal diameter of the carapace much 

 exceeding its length. Front inclined, but far from being vertical. 

 Lateral borders of the shell elevated, delicate, and very much cum 1, 

 and its lateral walls forming ordinarily a nearly straight angle with 

 its upper surface. Eyes nothing remarkable ; orbits directed 

 forwards and presenting almost always below their external angle a 

 wide and deep notch, which, as in Saarma, is continued backwards 

 with a transversal gutter hollowed out in the pterygostomian regions 

 of the carapace below its lateral border. Antennary pits much less 

 narrow than in Graptut, and the basilary joint of the externa 

 antenna! much less wide. External jaw-feet much resembling those 

 of Graptut : their third joint shorter than the second, wide as it in 

 long, enlarged anteriorly and strongly truncated at its anterior bonier; 

 a small projecting and piliferous crest runs obliquely from the air 

 and interior angle of this joint to the posterior and external angle of 

 the preceding joint, so as to form with that of the opposite side a 

 triangle, the base of which is backwards ; the external appendage of 

 these jaw-feet nearly reaches the anterior border of the third joint of 

 their stem, and terminates by a multiarticulate appendage. Feet of 

 nearly the same form and disposition as in Grajtiu, except that the 

 tarsus is not so large, and has no spines. 



The species are distributed in the seas of Asia exclusively. 

 (Milne-Edwards.) 



M. Milne-Edwards divides the genus into the following sections: 



A . Species having the lateral border of the carapace entire. 



a. A deep gutter springing from the external orbital gap and 



directed forwards. 



C. punctaitu. Length, 15 lines. Locality the Indian Ocean, 

 a a. No well-marked post-orbital gutter. 



C. integer (Grapttu integer, Latreille). Length, 4 lines. Locality 

 Brazil. 



B. Species the lateral border of whose carapace is dentated. 



4. External orbital gap but little marked. Orbita directed forward. 

 C. quadridentatia. Length, 10 lines. Locality, Australia. 



b b. External orbital gap very wide. Orbits very oblique. 



C. LatreUlii (Graptiu renotia, Latreille). Length, 4 lines. 

 Locality, Mauritius. 



Pteudoyraptut (Milne-Edwards). M. Milne-Edwards observe* th.it 

 one of the characters pointed out with reason by M. Latreille as 

 distinguishing the natural groups of Graptut and Playiuia is the 

 having the external jaw-feet narrow and notched on their internal 

 border, so that these organs, instead of closing the mouth completely, 

 leave between them a vacant lozenge-shaped space ; but he remarks 

 that this disposition is not met with in all the species which are 

 usually arranged under the genus Grapna ; and as these modifications 

 of the buccal apparatus coincide with other characters, and seem to 

 indicate a natural division among these animals, he has taken it as the 

 basis of their classification, and proposes for those walking Urap- 

 soidious whose mouth is completely closed by the external jaw-feet 

 the name of Ptevdograpnu, with the following generic character : 



General form approaching that of Cyclograptui more than that of the 

 other Orapsoidiaus, the body being thick, and the carapace, convex 

 above, being rather regularly rounded on the sides. Basilary joint 

 of the external antenna! nearly square and joined to the front, its 

 external border being in contact with a vertical tooth which elevates 

 itself on the floor (plancher) of the orbit, as in Macrup/ii.'. 

 and the Ocypodions. Internal border of the second and third joint 

 of the external jaw-feet straight, and this last joint, remarkable for 

 being much wider than it is long, presents in the middle of its 

 anterior border a notch whence springs the terminal stemlet (tigelle). 

 Sternal plastron nearly circular, and slightly curved from before 

 backwards. Anterior feet of the male very large, and much longer 

 than any of the succeeding feet, which are rounded and terminated 

 by a hairy tarsus, and completely deprived of spines. Abdomen of 



