MEMOIRS OK THE NATIONAL ACADEMY OF SCIENCES. 373 



far north as Virginia. From Florida and Cuba nine species are recordeil. I have found twelve 

 species of this prolili(; jjcniis, or altout one -half the nmnher described for the whole American con- 

 tiueut, inhabiting the beautiful little reef of growing coral called Oix Point to the eastward of 

 Nassau Harbor and along the margins of the little bay which was just in front of our laboratory. 

 Another species (.1. irchsteri Kingsley), first reported from Florida, was also discovered on Green 

 Key reef, a few miles from Nassau. 



From collections which I made at Abaco and Andros Islands. I am led to believe that the 

 different species are quite g<nierally distributed in the liahamas, and as these islands have prob- 

 ably been largely populated from the South, we may expect tiie same forms to occur at Cuba and 

 at other West Indian Islands. This genus, howcs'er widely distributed, is essentially tropical and 

 abounds in all coral seas. Of the great family of the Crustacea which make their home on the 

 submergeil reefs of growing coral, Alpheus is perhaps the most proM)ineiit and thoroughly charac- 

 teristic. They pop out of almost every rock which is brought up from the bottom, and everj- loose 

 head or block of growing coral, with its clusters of alga", sponge, and sea fans, which you pull 

 from the reef, resounds with the click of their little hammers. •^ 



Some of these auimals lead a semi-parasitic life in sponges, or seclude themselves in the ])orou8 

 limestone which forms the solid lloor of the beach, and others, again, live under loose shells and 

 stones in the white coral sand. Some are highly and beautifully colored, and with few exceptions 

 the pigment is characteristic; of the species for any locality. In all cases the claws of the first 

 pair of walking legs are enormously enlarged and serve as formidable weapons of defen.se so re- 

 markable in this genus, and in most there is the greatest disparity in the size of these claws one 

 either the right or left, being the larger. One species, the habits of whi(!h are peculiar, carries 

 the larger of these claws so folded under the body as to be completely concealed. It can, however 

 quickly withdraw this weapon and make a rapid thrust when an enemy comes near.* By the scis- 

 sor like blades of the large claws a sharp metallic rejioit is produced. This is true of nearly all the 

 species, and so abundant arc many in these islands that a constant fusilade is kept up along some 

 of the shores at low tide. This snapi)ing jiropensity is shared by both sexes whether in or out of 

 the water, and it is undoubtedly correlated with their pugimcious habits, [f two males or females 

 of the same or different species are i)laced in the same aquarium, they will dismember each other 

 in a very short time, and one is usually literally torn to pieces. 



The sounds emitted by Alpheus Jictcrochclis are the loudest I have heard from any meml)er of 

 this genus. We fre<pu'ntly kept this species in glass dishes in our room for several days at a time 

 and sharp reports like the explosion of a small torpedo or pop gun were heard at intervals through 

 the day and night. It sometinu's swims with its large claw so widely opened as to suggest dislo- 

 cation. This weaj)on then reminds one of a cocked jjistol, and the report ai)parently follows in 

 the same way that the click follows the impact of the hammer on the lock. 1 have given this 

 mattter no closer attention, but find that Mr. Wood-Mason, who is quoted in a notice on " Stridulatiu"- 

 Crustacea" t in "Nature," (05) has ofl'ered anoth(>r explanation. According to this observ<'r the 

 sound always accompanies a sudden oi)ening of the elaws to their fullest extent, and may be caused 

 either by impact of the dactyle upon the joint to which it is articulated or "by forcible withdrawal 

 of the huge .stopper-like tooth of the dactylopodite from its pit in the immovable arm in the claw." 

 It seems most probable to me that the sound is caused l)y impact, and most likely by the rapid 

 closure of the finger into its socket. | 



* This sppcii'H is ontirely new. TIip large conooiilod claw suggests a poison apparatus. Tlio " fingers " aj»es.- 

 ceediugly slender and sharp at the points. Although kept for over a week in an .aqii.ariiini it emitted no sonnds. 



♦ According to Wood-Ma.son sonnd-prodncing organs in Crnsfacea were first hronght to notice by Iliigenilorf, in 

 V. dcr Decker's "Roiscn in Ost-Africa (Crnstaccen)," and were afterwards observed hy liiinself in liis dredgin" ex- 

 pedition to tlie Andaman I.slands. The stridnlating organs— scr.ipers and rasps — may be either ou the carapace and 

 appendages or on the appendages alone. 



! Hotli Kent and Wood-Mason speak of the soiinds emitted by the Alphei as if prodnced by the extension or 

 opening of the claw. As pointed ont above, it is jnst tlio other way, the sonn<l following upon the imp.act of dactvle 

 and [iiopodns, when the tooth of the dactyle is not pnlled out of its socket but driven into it. None of the coiulitions 

 of piston movement are present. The walls .and floor of the pit are relatively soft, while the tips of the elaw are 

 dense and stony. The "click" can be .artificially produced when the claws are clamped with rubber, whether the 

 "stopper " is present or not. 



