ZOOLOGY. 31 



it fines off rapidly to seaward, until, a little way out, pure mud is rcaclRd. In 

 some parts, at low water, a very tliin layer of sand covers the mud below. This 

 mud is exceedingly stilt, and of the colour of the well-known blue lias. To come 

 now to the manufacture of tliese stones. The crabs, which abound on tropical 

 seashores, were here, although too small to be worth catching f(jr the pot, con- 

 siderably larger than I had seen in similar situations elsewhere ; and, as the tide 

 was low, we saw numbers of them runing about the wet sands, and, as wo ap- 

 proached them, they would dive rapidly down into the small round holes which it 

 is their habit to burrow for themselves. In making these holes the crabs (as is, no 

 doubt, known to many) throw out the soil in small round pellets or balls. I had 

 fretpiently noticed at Amherst the tmy round balls of sand strewed about the holes 

 which the smaller crabs there make. When the ejected material is sand, these balls 

 are, of course, at once dissolved at return of each tide, lint here, as the sand was 

 only in a superficial layer, and the crabs were larger, in making their holes they 

 penetrated thi-ough the sand and reached the mud ; consequently the material thrown 

 up was stiff clay, and the balls were larger in proportion to the size of the workers. 

 Looking at these balls of clay as the tide was turning to flood, we soon perceived how 

 our stones were made. The ripple of an advancing wave would first roll two of the 

 smaller balls into one, then another wave would do the same with two larger ones, 

 until, by a repetition of this very simple process, rounded balls of various sizes were 

 formed, and ultimately, as tlie tide advanced, flung up high and dry upon the sand, 

 out of the farther reach of the waves. Here they lay and hardened, until, in form, 

 in weight, and in general appearance, they resembled hond-fde water-worn fragments 

 of blue lias. There was a long line of these stones on the .sand just above high- 

 water mark, and they must have been numbered by thousands." 



An eiiually common crab, a species of ^•Gela-iimus, is mentioned by Dr. llason. 

 It especially att'eets tidal creeks and mud banks, and the males are jjrovided with one 

 huge claw, which they hold up as though threatening or beckoning to some one. 

 They are vci-y agile, and despite their defiant attitude, C[uickly disappear down a 

 hole if an effort is made to catch them. 



Family PortunidsB. 



Go2n.soMA noPLiTES, "Wood-Mason. Bay of Bengal. 



,, CKDCiFEKUM. Akyab. 



„ DENATUM. 



,, sp. Akyab. 



NePUTNTTS GLADrATOE. 



,, GRACILIJIANCS. 



„ PELAGICUS. 



,, SANGT7IN0LEXTUS. 



„ sp. 



Thalamita squamipera. 



AcHELOUS WuiTEI. 



Family Cancridse. 

 Cancer strigatps, Herbst. 



ZoZTMUS .SNEUS. 



Epixanthus frontalis. 



Ozrus eugulosus, Stimpson. Nicohars. 



LyoTonrus sanguineus. 



UlERGATIS DILATATUS. 



QUADEELLA COEONATA. 

 EarPHIA LEVIMANA. 



Lambeus CAEINATUS. 

 SCYIXA SEEEATA. 



Family Eriphidse. 

 Family Parthenopidae. 



