70 THE MICROSCOPE. May., 



spoke of a page or two back. The genera Lithobotrys 

 and Botryocella instead of lacking a mouth, as would ap- 

 pear at first sight, are said to have the mouth closed. It 

 will puzzle the beginner to find any trace of a mouth in 

 the shell, and he must accept the fact on the authority of 

 Haeckel who gives us this distinction. At the same 

 time he will readily recognize the general resemblance 

 of these forms to all the rest of the Botryodea by the 

 presence of the peculiar lobes, and as many of them 

 have a mouth it will only require a slight stretch of the 

 imagination to believe that in these forms the mouth has 

 been closed by an abnormal growth of the lower part of 

 the shell. At any rate they do not at all resemble the 

 Spumellaria in shape, and if we had the living forms 

 before us, we should undoubtedly find that the openings 

 in the capsule (the inner portion of the protoplasmic 

 body of the animal), were confined to the area facing 

 what is called the closed mouth. In the last Fam. of 

 this order, the Pylobotryida, the forms have three joints, 

 cephalis, thorax, and abdomen (see Fig. 28), the abdomen 

 being simply the lowest joint of the three. 



In the last order, the Cyrtoidea, the cephalis is simple, 

 that is, it consists of only one chamber, (see Fig. 29). 

 It has -no internal partitions, dividing it into two cham- 

 bers, as in the Spyroidea, or into many lobate chambers, 

 as in the Botryodea, and the general shape of most of 

 the forms is that of a cone. This is an immense order, 

 comprising no less than 79 genera. But it is divided 

 into four sections, which are very clearly distinguished 

 by the number of the joints in the shell, thus : — 



Section A, one joint — Cephalis only ; Fig. 29. 



Section B, two joints — Cephalis and thorax ; Fig. 30. 



Section C, three joints — Cephalis, thorax and abdomen; 

 Fig. 31. 



Section D, four to seven or more joints in the shell; 

 Fig. 32. 



