MAZATLAN UNIVALVES 421 



Tablet 1972 contains 9 sp. very young. 1973, 8 do. adoles- 

 cent. 1974, 9 do. adult, various sizes. 1975, 3 do. repaired 

 after fracture. 1976, 2 sp. with opercula. 1977, 1 sp. beauti- 

 fully encrusted, another with broken lip shewing the fold 

 within, and 2 dead sp. in which state the details of sculpture 

 are conspicuously marked. 



508. CHRYSALLIDA TELESCOPIUM, n. s. 



Chr. t. conicd, turrit d, alba ; vertice nucleoso, satis promin- 

 ente, anfr. ii. helicoideos verticaliter sitos continence, apiceparum 

 monstrante, marginibus spirce (testa adolescente) rectis vix 

 super ante ; anfr. vii. normalibus, quarum v. planati, in spird, 

 ut in "Chr. communi," clatkris circiter xvi. et lirulis spiralibus 

 iv. decussatis : testa adolescente, lacuna suturali impressd circa 

 basin continud ; peripheria angulata, apertura subquadrata ; 

 testa adultd, basi hand angulatd, effusd, haud lacunatd ; peri- 

 tremati continuo, ad basin late sinuato : basi lirulis spiralibus 

 circiter vii. cinctd, interstitiis vix decussatis ; plied columellari 

 intus acutd, prominente, ad aperturam vix monstrante, declivi. 



This species begins life as a helicoid body, rather large in 

 proportion as in Chemnitzia, which genus it also approaches in 

 the number of whirls. These a,re flat, with straight margins, 

 having the basal periphery angulated in the adolescent shell, 

 in which state it approaches the form of Telescopium. The 

 sutural groove, formed by the hollowing off of the ribs in the 

 last cancellated division, is then continued round the base. In 

 the last whirl however, the shell is contracted, the base pro- 

 duced, the sutural groove evanescent, the aperture effuse, and 

 a strong continuous labium finally appears. It is known from 

 Chr. communis by the large size of the vertex, taking off the 

 appearance of truncation from the shell ; in the non-adult state 

 by the greater angulation of the base and antesutural groove 

 (the ribs in the common species not quite reaching the suture) ; 

 and in all states by the greater divergence, and by the basal 

 striae, which are stronger and less numerous. A specimen in 

 the angular state measures long. *082, long.spir. '055, lat. '037, 

 div. 30. One almost adult measures long. "125, long. spir. '085. 

 Hob. Mazatlan ; 10 specimens (mostly young) off Chama and 



Spondylus ; L'pool Col. : do. 3 sp. (one adult) ; Havre Col. 



Tablet 1978 contains the youngest sp., with two and a half 

 normal whirls ; an angular specimen with 5 whirls ; a perfect 

 sp. with 6 whirls, normal form, but without the parietal lip ; 

 Dec. 1856. nn. 



