312 AlI^S MCDO]S'ALD AXD DE. TEVEMAX OX [vol. Ixxvil, 



Dimensions of our specimens. 



T /7 -D J.J T J.1 J' ■ Spiral Sutured 



L.enqth. Breaatli. Lenqtli of spire. -^7 7 



^ ^ J -f angle. angle. 



6-5 mm. 32 per cent. 69 per cent. 23° 107'' 



Our specimens appear to be identical with Dumortier's species ; 

 they are slender turriculate shells, havino- flat whorls ornamented 

 with three rows of tubercles, and separated by fairly deep sutures. 

 The oral margin is yery rarel}' seen, but is always simple, and if 

 an}" sinuosit}'^ is present it is yery minute. 



Deyelopment (see fig. oa'). — The apex shows a smooth em- 

 bryonic whorl; little more than one yolution in length ; a single 

 spiral then appears in the anterior region, and by the succeeding 

 whorl a second primary spiral is added aboye the first ; this type 

 of ornamentation lasts for two yolutions, and then axials are 

 deyeloped, in such wise that two rows of tubercles joined by axial 

 and spiral lines are produced. In the following whorl a single 

 secondary spiral is intercalated between the two primaries, with the 

 formation of three rows of tubercles, the pattern characteristic of 

 the remainder of the shell. Owing to the prominence of the two 

 primary spirals the whorl appears flat, and the borders of the 

 sutures pronounced. 



Locality and horizon. — The specimens were collected from 

 the Lower Liassic clays of the tunnel-heaps, Old Dalby, Leicester- 

 shire (probably near the oxipiotus zone). Similar specimens have 

 been found by Mr. L. Richardson in the turneri zone, near 

 Hester's Way Farm, in the neighbourhood of Cheltenham. 

 Dumortier's specimen is also recorded from the oxijnotus zone. 

 Typical specimens ha ye been presented to the British Museum of 

 Natural History (G 24873-74.). 



Peoceeithu'm cf. QTJiJfQTJEaEAjS^osFM Cossmann. 



Froceritliitim quinq^iiegranoswn Cossmann (3, pi. iii, figs. 1-3). 



Dimensions of our specimens. 



-r ,7 -D 1x1 T J.1 -c • spiral Sutural 



Length. Breadth. Length of s:p ire. ^^^^^_ ^,^^^^ 



6-6 mm. 34 per cent. 70 per cent. 25° 103° 



Small specimens, with flat whorls separated by deep sutures : 

 the ornamentation of the adult whorls consists of five rows of 

 nodules. Oral margin simple. 



Deyelopment. — The apical whorls are, unfortunately, not 

 preserved in our specimens, but the two earliest whorls present are 

 ornamented by two spirals ; these are followed by one Avhorl with 

 two rows of nodules, formed by the two spirals crossed by straight 

 axials. The succeeding whorl has three rows, and is followed by 

 two whorls with fom* rows of nodules ; by this time, howeyer, the 

 axials have become curved, and the remaining wliorls haye the 

 characteristic fiye rows of granules, which give the name to the 

 species. It is interesting to note that the two primary spirals 



