154 THE SEA. 



surface is brought into contact with the food ; it is 

 there embraced, and, as one may say, swallowed, and 

 there digested ; so that any part of the simple glairy 

 body may become a temporary mouth or an impro- 

 vised stomach. Generally, the residuary portion of 

 the food-pellet is slowly pushed out and rejected at 

 the nearest point of the surface ; but not always ; for 

 these exuviae sometimes accumulate in considerable 

 numbers, so as even to choke up a large part of the 

 cavity of the shell. 



Nearly two thousand species of these little creatures 

 have been distinguished, and they are doubtless much 

 more numerous than this ; oil are not microscopic, 

 some of the oceanic species being of the size of a shil- 

 ling, and a few even as large as a crown-piece. There 

 is great diversity of form in the shells : some are 

 straight or curved rods ; some conical ; some have the 

 shape of elegant vases or bottles ; some are orbicular, 

 many discoid, and the majority spiral. The shell 

 appears to be invariably simple in its first stage, being 

 deposited around a primal nodule of sarcode ; this is 

 the first chamber : buds develop themselves in succes- 

 sion from this, each of which deposits its calcareous 

 chamber : thus successive chambers are formed. If 

 these buddings take place in a right line, the mature 

 shell will be rod-like, or necklace-like ; but if the axis 

 of development incline slightly to one side, a curved 

 rod, or row of beads, will result ; if this inclination 

 be in excess, a spiral growth will be formed, the cha- 

 racter of which will be modified by the ratio of 



