ACL1S. 99 



Shell small, conical or pyramidal, smooth or variously sculp- 

 tured : spire pointed, with an inflected and mostly a reversed 

 apex : mouth oval, somewhat angulated but not channelled 

 below: outer Up thin: operculum ear-shaped, with a short 

 imperfect spire of very few whorls ; nucleus excentric, on the 

 inner side near the base. 



This family contains several genera, some of which 

 (especially Odostomia) abound in prolific species. They 

 are widely diffused over the present marine area of our 

 globe, and appear to have had an equally extensive range 

 in periods which we call geological. The Pyramidellida 

 inhabit all the zones, and are probably sarcophagous, 

 not zoophagous or predaceous. Their shells are grace- 

 ful in shape, and often beautifully sculptured ; but, being 

 minute, they can be appreciated by those only who have 

 accustomed themselves to see 



" Form in things which to the eye 

 Half-read is but deformity — 

 Grandeur in mean things and small, 

 And Grod's great handiwork in all ! " 



Although it does not appear that any direct obser- 

 vations have been made as to the reproductive system 

 of the PyramidellidcE, it may be inferred from an un- 

 published drawing by Moller of the soft parts and oper- 

 culum of Monoptygma albulum [Turbo albulus, Fabri- 

 cius) , which is allied to Aclis and belongs to the present 

 family, that the sexes are distinct. In that drawing 

 (for a tracing of which I am indebted to Dr. Morch) 

 the male organ is very conspicuous. 



Genus I. ACLIS * Loven. PL II. f. 4. 



Body slender : tentacles long, approximating at their bases : 

 eyes placed rather more on the outer than the inner base of 

 the tentacles. 



* A small javelin. 



f2 



