366 ME. E. S. C'OBBOLD OS THE [vol. lxxvi, 



growth are very irregular, varying in strength from one part of their 

 course to another and running one into another, so that there are 

 no well-denned step-like anirulations ; the radiating stri* are, on 

 the other hand, quite regular: they increase by interpolation, and 

 are spaced about seven to the millimetre. 



Dimensions of largest specimens. — Length =17 mm. ; width = 

 15 - 5 mm. ; greatest height = 7 mm. ; height of apex = 4 mm. 



Locality and horizon. — Comley, Lower Cambrian; from the 

 Olenellus Limestone, horizon Ac.,, and from the Callavia Sand- 

 stone, horizon Ac,. 



Latoitchella, gen. nov. 



Diagnosis. — Shell small, calcareous, coiled or incipiently coiled 

 so as to be isometrical about the median plane ; aperture elongate, 

 entire, not notched ; whorls free, not in close or overlapping 

 contact. 



Type-species — L. costafa, sp. nov. 



Horizon. — Lower Cambrian. 



The incipient coiling and elongate aperture are reminiscent of 

 Platyceras, from which these shells differ in having the apex on 

 the median plane. 



In side view they approach some forms of Helcionella, particu- 

 larly JEL. pcmpera Billings, but they are without encircling annula- 

 tions or rugosities. 



The absence of a notch in the apertural margin seems to preclude 

 a reference to any of the Heteropod-like shells, such as Pelagiella 

 Matthew, TVatsonella Grabau, etc. 



The external resemblance of L. costata to an immature ammonite 

 is remarkable ; there are, however, no indications of septa. 



Latouchella costata, sp. nov. (PI. XXIY, figs. 41 &42.) 



Type-specimen in the collection of the Rev. W. M. D. La Touche, 

 of Wistanstow, Craven Amis. 



Diagnosis. — Shell consisting of about one and a quarter whorls ; 

 aperture OA r al (ratio of diameters about 1 to *5) and slightly 

 campanulate ; sides provided with six to eight or more elongate 

 prominent ribs, swollen towards the convex margin of the shell, 

 which they do not cross, and narrowing to disappear in the opposite 

 direction, these are reproduced in the interior : whorls standing 

 clear of one another in the internal cast, probably just touching 

 one another in the complete shell. Dorsum narrowly rounded, but 

 not keeled. 



Dimensions of the larger specimen. — Apertural diameters 

 = 4x2 mm. ; total length = 45 mm. ; height = 2 - 5 mm. 



Locality and horizon. — Comley, Lower Cambrian; from the 

 Olenellus Limestone, horizon Ac 3 , and from the JProtolenus 

 Limestone, horizon Ac 3 . 



