214 Dr. W. T. Caiman on MiiuiJopsls polymorpha. 



Laiizarote. They belong to the species described by 

 Dr. Koelbel under the name Munidopsis polymorpha from 

 specimens collected in the same locality by Prof. Simony *. 

 Koelbel's account of the species and of its remarkable habitat 

 appears to have been overlooked by subsequent writers on 

 the Galatheidai t> ^'i^ i^ "i^J ^6 worth while therefore to 

 draw attention to it again. 



1'he eave in which these Crustacea are found forms part of 

 an extensive system of caverns known collectively as the 

 " Oueva de los Verdes '^ I, ramifying through the lava-beds 

 in the northern part of the island. In one of the chambers, 

 at a distance of about half a kilometre from the sea, there is 

 a pond or small lake of salt water, which communicates with 

 the sea by subterranean channels, the water in it rising and 

 falling with the tide §. The size of the pond is given by 

 Pi of. Simony as about 40 metres in length by 15 to 20 metres 

 in breadth, with a depth of 2 to 8 metres. Tlie cavern is 

 dimly lighted by an aperture in the roof. Mr. Prevost found 

 in the water no vegetable or animal life other than the Muni- 

 dopsis, which is sometimes present in large numbers. The 

 animals are described as being of a "pale reddish yellow^' 

 colour when alive, and Prof. Simony adds that they " ersch- 

 einen vernioge der Wirkung complemeiitarer Farben fast 

 weiss.''^ This remark is exjilained by Mr. Prevost's state- 

 ment that in the dim light of the cave the water appears of a 

 beautiful blue colour. 



As regards the characters of the species, I am unable to add 

 anything of importance to KoelbePs excellent and minute 

 description. The great variation which he found in the shape 

 of the rostrum and the armature of the carapace, and which 

 is alluded to in the sjjecific name, is well exhibited in the 

 series of specimens examined by me. The exact position of 

 the species in relation to the very numerous species of Muni- 

 dopsis described since KoelbePs paper was written is not easy 



* Koelbel, " Beitr. z. Kennt. d. Crustaceen d. Canarischen Inseln," 

 Aun. naturhist. Hofmuseums, Wien, vii. (3) p. 109, pi. x. figs. 3-16 

 (18'J2). 



+ The species is omitted from Dr. Benedict's list of the Galatheidoe, 

 Proc. U.S. Xat. Mus. xxvi. pp. 300-334 (1902), although the reference 

 duly appeared in the ' Zoological Kecord ' for 1892. 



X For a general account of the caves see Hartung, " Die geologischen 

 Verhaltnisse der Inseln Lanzarote nnd Fuertaventura," Xeue Denkschr. 

 allg. Schweiz. Ges. ges. Naturwiss. xv. (4) p. 81 (1857), where, however, 

 the pond is not mentioned. 



§ A sample of the water brought home by Mr. Prevost has been 

 analysed by Mr. A. J. Robertson, B.Sc, of Univei-sity College, Dundee, 

 w\v> kindly informs me that it has a salinity of 35-39 per mille, which is 

 prob.ibly about the same as that of tlie >e;t outside. 



