NOTES ON THE CAMBRIDGE GREENLAND* 493 



possessing three rows of tubercles instead of four, yet there are 

 many characters common to the two species ; and it must be remem- 

 bered that tubercles are sometimes represented by ribs as in T. 

 eostatus. 



Altogether I consider that the above-mentioned species hold such 

 relations to one another as make it only reasonable to suppose that 

 they have been produced by descent with modification. 



The Cambridge form might receive the name of T. canta- 

 brigiensis* 



? Turrilites Emericianus, D'Orb. 



Turrilites Emericianus, D'Orb. Pal. Pr. pi. cxli. figs 3-5. 



The Woodwardian Museum possesses a small dextral cast, which 

 appears to be referable to the above species, or is, at any rate, very 

 closely allied to it. 



Only two whorls are preserved ; but these are sufficient to show 

 its low squat growth, and to distinguish it from T. Hugardianus. 

 These whorls are rounded and ornamented with about 24 simple 

 straight ribs, running down into the umbilicus, which is wide and 

 ample. 



Turrilites elegans, D'Orb. 



This species does not yield a very well-marked cast; several 

 specimens, however, have passed through my hands which greatly 

 resembled it ; one of these is now in the Museum at Jermyn 

 Street. 



Turrilites nobilis, new sp. PL XXI. fig. 1. 



Cast rather large, dextral, whorls full and rounded, crossed some- 

 what obliquely by 26 to 28 well-marked ribs, each bearing three 

 small tubercles ; the lower row of these is only seen on the body- 

 whorl, being sutural in the whorls above. The ribs appear to run 

 under the base, and to converge towards the umbilicus, their 

 impressions being seen on the broken uppermost whorl. 



The spiral angle is very small ; and the whorls were probably nume- 

 rous, as in T. Hugardianus, from which it is easily distinguished by 

 the rows of tubercles. The specimen above described was collected 

 during the progress of the Geological Survey ; and the last whorl 

 of a cast apparently belonging to the same form is preserved in the 

 Woodwardian Museum. The actual shell is unknown, but was 

 probably thin, as in other Turrilites ; so that its characters are suffi- 

 ciently delineated by the cast : I have therefore thought that the 

 species might safely be described and named. From T. Wiestii 

 it is distinguished by the broader whorls and less prominent 

 tubercles, in this respect approaching T. Escherianus, 



