84 



QUEKETT'S LECTURES ON HISTOLOGY. 



Fig. 141. 



Pedicellarice of Spatavgus 

 purpureus 



of the ' Histological Catalogue,' in having more than one hooked process 

 extending outwards from the point where the curved portion commences. 

 Under a power of 40 diameters, as shown at a, in fig. 109, numerous 

 Pedicellaria? are distinctly visible on the 

 upper dermal surface of Aster ias rubens, even 

 after having been dried ; but as the soft fleshy- 

 stalk is very short and has no calcareous 

 axis, little can be seen except the jaws, 

 redicellarise also exist in the SjMtangi, but 

 they are not so evident as in the Echini ; the 

 principal varieties found in S. purpureus, 

 according to Forbes, are represented in 



fig. m. 



" The Pedicellarise then, without doubt, 

 belong to the animal on which they are 

 found ; they are not parasites, but it is diffi- 

 cult to determine their true office ; they are 

 probably useful in keeping the shell free from all intruders of a parasitic 

 nature, and may be supposed to perform an analogous function to that of 

 the so-called ' Bird's-head processes' of the Bryozoa." 



The MoUusca and Articulata are treated of after the 

 Echinodermata, The shells of the principal families of the 

 Mollusca are examined in detail, and many new^ points in 

 their structure described and illustrated. The Articulata are 

 not treated so much in detail. In these concluding lectures 

 we had marked some passages which we should have liked 

 to have transferred to our pages. We have, however, given 

 sufficient for our readers to form an estimate of the work, 

 which we are sure will be of such a kind as to lead them 

 to feel that it is one of great value to the microscopical 

 student. The illustrations are very copious, and every one 

 will be able to form an opinion of their excellence from those 

 we have eiven above. 



