Mr. W. Clark on the Animal ^/Dentalium Tarentinum. 321 



lated, reticulation regular with quadrangular areolse, and covered 

 with many slender linear tubular spines or their bases^ somewhat 

 quincuncially arranged ; spines smooth, dilated at the base, a 

 little above which they remain of nearly uniform size throughout 

 or very slightly tapering, and are regularly and transversely sul- 

 cated or contracted, giving the spines a beaded or jointed ap- 

 pearance. 



The general form of the shell and quincuncial arrangement of 

 the spines resemble S. aculeata, Kutorga, but as that author does 

 not figure or allude to any reticulated structure or the monili- 

 form spines*, this is considered to be distinct ; unfortunately 

 the specimen is much compressed, so that all the characters are 

 not fully shown, and I have provisionally given the name of 

 S. anglica until it can be compared with all the Russian species. 



Locality. From the Wenlock shale near Dudley. Collection 

 of Mr. J. Gray. 



EXPLANATION OF PLATE VIL 



Fig. 1. Siphonotrela anglica. a. Shell, natural size. h. Shell, magnified 

 view. c. Spines enlarged, d. Portion of ditto, magnified, e. Outer 

 surface of shell, magnified. 



Fig. 2 a. Siphonotreta verrucosa, b. Side view. c. Surface of shell, mag- 

 nified, d. Interior of dorsal valve. 



Fig. 3 a. Schizotrefaz= Orbiculoidea, D'Orh., O.Forbesii. b. Showing lon- 

 gitudinal furrow and contracted perforation. 



Fig. 4. Acrotreta=. Cyrtial a. Dorsal valve, b. Ventral valve. 



Fig. 5. Aulonotreta = Obolus. 



XXXIII. — On the Animal o/Dentalium Tarentinum. 

 By William Clark, Esq. 



To the Editors of the Annals of Natural History. 



Gentlemen, Norfolk Crescent, Bath, Sept. 1, 1849. 



The animal I am about to present to your notice exhibits a 

 series of characters of the highest interest, in its anatomy and 

 functional developments, some of which are so anomalous that 

 it must be considered one of the most singular of the testaceous 

 mollusca. 



From my observations in the September Number of the ' An- 

 nals,' it appears that the minute species of the genus Cacum, 

 from their configuration, have generally been located with the 

 Dentalia, though it will be seen that there is little concordance 



* The moniliform character of the spines may not be peculiar to this 

 species, but will probably be found to belong to the whole genus, when the 

 spines of the other species are carefully examined by a higher mcignifying 

 power than that used by Dr. Kutorga. 



Ann. ^' Ma^. N. Hist. Ser. 2. Vol. iv. 22 



