VI 



TIIALASSINIUEA ANOMURA I 67 



right on In-, rather goes to show that this is the primitive mode of 

 development in the Decapocla, and that the disarrangement in the 

 order of appearance of the segments, both in the Squillidae and in 

 the Loricata and other Decapods, has been independently acquired 

 in the two cases to meet the needs of the larval existence. 



Fam. 1. Palinuridae. The cephalothorax is subcylindrical, 

 the eyes are not enclosed in separate orbits formed by the ed-e 

 of the carapace, and the second antennae possess flagella. 

 f'ft/r/ii/i'us, with P. ehpkas, the European Rock L<>l>M<-i or 

 Langouste. losus with two species in the Antarctic littoral : 

 Panv.li.riix in the tropical littoral. 



Fam. 2. Scyllaridae.- -The cephalothorax is depressed, tin- 

 eyes are enclosed in separate orbits formed by the edge of the cara- 

 1'ai-e, and the second antennae have flat scales in the place of flagella. 

 ScyllariAS ( Kig. Ill), with the European S. arctv.s ; ll<n-n* in rather 

 deep water with several species, chiefly found in tin- southern 

 hemisphere. 



Tribe 6. Thalassinidea. 



This tribe is included by some authors in the Anomnra, and 

 ln-ld to IK.- closely related to the (ialatheidea, hut the unreduced 

 abdomen is carried straight and unflexed, and gives a very 

 Macrurous appearance to the animal. The Ariomurous ehar- 



era are the frequent reduction or absence of the antenna 1 

 scale, the fact that only the first two pairs of pereiopods are ever 

 ehclale.and the reduced series of gills. The body is symmetrical, 

 but the first pair of chelae is always highly a.-ymmet i ical. The 

 posterior pairs of pereiopods, although small, ai'e not chai-ad 

 istically reduced as in the Anornura. Tlu^ animals belonging to 

 this Tribe attain two or three inches in len-tli, and geiierall\ 

 burrow in .-and or mud either in the littoral /one or in deepn 

 uatei>: at the same time thc\ caii swim with considerable 

 activity by means of the pleopods. 



Fam. Callianassidae. ('<illi<niii*xii subterranea is common 



at Naples, di'liin. litftirnlix in the North Sea. 



Sub-Order 2. Anomura 



In this division are included the so-call>d I lenrit -|i ' and 



Hermit-crabs, in which the condition of the abdomen i hly 



intermediate b. i ween thai of t he Macrura and that of the I 1 , radix in a. 



