FOURTH REPORT OF THE DIRECTOR I907 1 67 



FistuHpora occidens presents a similar coalition of a 

 hydroid coral and the primitive tubulate Aulopora. This species 

 was described from the Upper Devonic Lime Creek shales of Rock- 

 ford, Iowa, by Hall [N. Y. State Mus. 23d Rep't. 1873. p. 228, 

 pi. 10, p. 9, 10] who recognized the fact that the large pores on 

 the surface of the coral are projecting tubes of Aulopora. An in- 

 teresting feature of this concurrence is that colonies of the Fistuli- 

 pora are quite as frequently without the Aulopora as with it. 



One may compare with these instances the interesting case 

 mentioned by Whitfield of the recent coral Ctenophyllia, entirely 

 inclosed by a hemispherical growth of Meandrina labyrin- 

 thica (described in Am. Mus. Nat. Hist. Bui. 1901. 14: 221). 



In addition to the instances given above of actual commensal 

 conditions, I am taking this occasion to append a brief account of 

 certain ancient pseudoparasitic organisms of boring habit. These 

 come frequently under the eye of the paleontologist but very little 

 attention has been given to them, occasional incidental references 

 being for the most part the sum of our knowledge of the Paleozoic 

 expressions. The literature of the later formations contains random 

 accounts of such organic relics but I should be going too far afield 

 in this instance to make definite allusion to these. ^ 



These boring bodies infesting the dead shells which form a large 

 part of the material of the paleontologist are very likely to be either 

 minute algae or fungi, or sponges of genera producing similar effects 

 to the living Cliona or Vioa. The work of the former has had some 

 notice [see Duncan Quar. Jour. Geol. Soc. 1876. p. 205; Kolliker. 

 Zeitschr. Wiss. Zoolog. 1859, 10: 215; Loomis, N. Y. State Mus. 

 Bui. 39. 1900. p. 223] and their tubules are recognizable by contrast 

 by their microscopic size and the occasional presence of hyphal 

 swellings. The total amount of deterioration and disintegration 

 of skeletons caused by these minute organisms was doubtless 

 great even in Paleozoic times. 



The work of boring sponges, however, on ancient organisms has 

 been a far more effective cause of destruction and waste of dead 

 shells. There are certain conditions of preservation in which these 

 borings enforce themselves on the attention, especially when the 

 student has to deal with an arenaceous matrix from which all the 

 calcareous matter of the shells has been dissolved leaving sharp 



'Very instructive instances of these later expressions are cited in a recent paper by E. 

 SchUtze, Die bohrenden und schmarotzenden Fossilien dor schwiibischen Mcercsmolassc, 

 Jahresb. d.Ver. f. vatcrl. Naturk. in Wtirtt. 63, 1907. p. 81-84; IJericht ueb. 29 Versaniml. 

 d. Oberrhein. geolog. Vereins zu Worth, 1906; Zeitschr. £. Mineral. Geol. u. Palaeont, 

 Jahrg. I. 



