PORIFERA OF THE L.M.B.C. DISTRICT. 219 



account of this comedy of errors I 

 refer to Leidy's recent paper "The Boring-Spouse, CUona f " 



Leidy, in his paper, also discusses the question whether 

 the CUona sulplmrea, Desor, of the American coast, which 

 is found both boring and massive, miglit be identical with 

 CUona celata, Grant, of Europe. He finds that the two 

 forms agree in all respects except two. Hancock t had 

 stated that in CUona eeUita, Grant, hexagonal siliceous 

 granules are found on the surface of the sponge, by which 

 the latter is able to work out the cavities it inhabits. 

 Leidy says he has not been able to detect those granules 

 in the American sponge. The second difficulty is : " Grant, 

 Hancock, Bowerbank, and Lieberkiihii give as the size of 

 the spicules of CUona celata about J^ of an inch, while in all 

 our ('i.e. American') forms of CU.ona, in the oyster and 

 clam, and in the largest massive varieties, the size of tlie 

 spicules is only about ^^ of an inch." 



The first difficulty about the hexagonal granules has 

 been solved by Topsent.§ He considers them as broken 

 pieces of the prismatic layer of the perforated shell, perhaps 

 intermixed with grains of quartz. In regard to the second 

 difficulty, Topsent remarks that the difference in size of 

 spicules cannot be of much value, as he himself has ob- 

 served spicules from 0"18 mm. to 0*35 mm. in length. On 

 page 217 I gave as the length of the spicules O'Blo mm. As 

 g'^inch is equal to 0-508 mm., and ^^ inch is equal to O'SIT 

 mm., we see that Topsent's and my own observations agree 

 with Leidy' s measurements as exactly as one could expect? 



* Bowerbank, "British Si>ongiad£e," vol. ii., p. 354 ; vol. iii., jil. Ixiv. 



t 111. "Pro. Acad. Xat. Sciences, Philadelphia," part i., January— April, 

 1889, p. 70. 



t Albany Hancock, "On the excavating power of certain Sponges belong- 

 ing to the genus Cliona," 1849. 



§ Emile Topsent, " Cliona celata on CUona sit'phurea f Bulletin de la 

 Society Zoologique de France," 1889, p. 351. 



