22 DE. T. DAVIDSON OX EECENT BRACHIOPODA. 



a few of its cirri and move them about, as if to ascertain if any danger threatened. 

 Only on one occasion a current was observed to set in on one side between the two rows 

 of cirri. I had been attempting to ascertain the existence of currents, by introducing 

 small quantities of indigo into the water surrounding the animal with a camel's-hair 

 brush ; three times the water was forcibly drawn in, and tlie particles of indigo were 

 seen to glide along the groove at the base of the cirri in the direction of the mouth." 

 See likewise a paper by Herouard " Sur les courants de nutrition des Bracliiopodes," 

 Journ. de Conchyl. vol. xxv. p. 229, 1877. 



Hancock * says : — " The pallial lobes extend forward, but do not project beyond 

 the side of the body, w^here they become united, the junction being marked by a groove, 

 bordered by a ridge on each side. They are very delicate and transparent, so that the 

 great pallial sinuses can be distinctly traced, even to their terminal ramifications " 

 (p. 793). "The arms of W. [TFaldhelmia'] cranium and T. caput-serpentis are 

 disposed in the same manner as in W. cmstnilis; and in the former the calcareous 

 loop is precisely similar to that of the latter ; but in T. caput-se)'pentis it is very much 

 reduced, the extended lateral portions having almost entirely disappeared, little more 

 than the transverse portion existing; and this, together with the crural processes, which 

 are united below across the median line, forms a collar upon which the bases of the 

 arms rest. In this species, therefore, the expanded lateral portions of the arms are 

 without any apophysary support, and accordingly other means are provided for sustaining 

 them. The two produced lobules of the dorsal pallial lobe reach to the ends of these 

 portions of the arms as in TP^. australls ; and are stiffened with numerous, imbedded, 

 calcareous spicula, to such an extent, that when the soft tissues are removed by mace- 

 ration the form of the parts remains unaltered. The spicula extend also over the 

 surface of the inner lamina of the pallial lobe, and pervade likewise the walls of the 

 canal, and even the cirri ; so that the brachial apparatus becomes firmly fixed, and in 

 this way a substitute is found for the usual apophysary support." (Loc. cit. p. 808.) 



It is, however, to Oscar Schmidt, so far as I am aware, that we are indebted for the 

 first notice of these remarkable sj)icula f , and in the Annals & Mag. of Nat. Hist. 2nd 

 ser. vol. xvi. p. 439, pi. x., I gave a translation, with figures, of Schmidt's observations. 

 The author remarks " that the mantle, oral arms, and cirri in Terebratulina caput- 

 serpentis contain an innumerable number of calcareovis plates, generally flattened, 



dilated and irregularly denticulated, situated in close vicinity to each other 



It is easily conceived [he adds] that these calcareous masses stiffen the parts which 

 contain them, and seem particularly to serve this function in the hollow cirri, thus 

 preventing their sides from sinking doAvn." 



We are also indebted to Prof. E. Deslougchamps for an admirable memoir ' Recherches 

 sur rOrganisation du Manteau chez les Brachiopodes articules ' (Caen, 1864), in which 



* Phil. Trans, vol. cxlviii., 1S58. 



t " Die ncusten UntersuchuDgen iiber die Braduopoden von Owen, Carpenter und Davidson, mit einigen 

 Zusiitzen," Zeitsch. f. gesammten Naturwissenschaften, p. 325, 18o4. In 1856, Dr. S. P. Woodward exhibited, 

 at a meeting of the Zoological Society, the spicnla in the pallial lobe of T. ccqjut-serjMiitis (Proc. Zool. Soc. 

 p. 368, 1856). 



