IN THE FORMATION OF CORAL REEFS. 



349 



DISTRIBUTION OF GORGONIAN COLONIES ON THE REEFS 



ABOUT TORTUGAS. 



In order to obtain a reliable estimate of the number of Gorgonian 

 colonies occurring on a considerable area of one of the typical reefs, a series 

 of counts (made by the use of the square-yard frame of iron pipe) were 

 made along a line running north-northwest from the laboratory wharf on 

 Loggerhead Key, extending across the west reef from its inner edge, over the 

 shallow crest and down its outer slope to a depth of about 6 fathoms. On the 

 shallower portion of the reef the counts were made about 40 feet apart. 

 Farther out, where the increasing depth of water made it impossible to 

 identify with certainty any of the species except Gorgonia flabellum and 

 Gorgonia acerosa, the counts were made about 60 feet apart until the 6-fathom 

 line was reached. Here the counts were discontinued, as dredgings had 

 shown that beyond this point the Gorgonian fauna is comparatively scanty 

 and for the most part made up of different forms from those occurring on 

 the reefs in shallow water. The results of this series of counts is shown in 

 table 3. 



Table 3. — Gorgonians counted on line across outer reef west of Loggerhead Key. 



1. Gorgonia acerosa I 



Plexaura flexuosa 2 



Eunecia crassa 2 



2. No Gorgonians. 



3. Plexaurella dichotoma I 



Gorgonia flabellum I 



4. No Gorgonians. 



5. Do. 



6. Gorgonia flabellum 1 



acerosa 1 15 



Plexaura flexuosa I 



Eunecia crassa 2 



7. Gorgonia acerosa 1 



Plexaura flexuosa I 



8. Gorgonia flabellum 2 



Plexaura flexuosa 4 



Eunecia crassa 4 



rousseaui 2 



sp I 



Briareum sp 2 



9. Gorgonia flabellum 2 



Plexaura flexuosa 2 



Eunecia crassa 1 



10. Gorgonia flabellum 2 



acerosa 2 



Plexaura flexuosa 2 



Briareum asbestum 1 



Pseudoplexaura crassa 1 



Eunecia rousseaui 1 



crassa 1 24 



n. Plexaura flexuosa I 25 



Eunecia crassa 5 



rousseaui I 



1 2. Plexaura flexuosa 4 



Gorgonia flabellum 1 



Plexaurella dichotoma 2 



sp ' 



Eunecia rousseaui I 



crassa 2 



Gorgonia flabellum I 



Plexaura flexuosa 3 



Eunecia crassa 4 



rousseaui 2 



Gorgonia acerosa I 



flabellum I 



Eunecia rousseaui 2 



Plexaura flexuosa I 



Eunecia rousseaui 2 



Plexaura flexuosa 2 



Pseudoplexaura crassa 2 



Gorgonia flabellum I 



Plexaurella dichotoma I 



Eunecia crassa 2 



No Gorgonians. 



Plexaura flexuosa I 



Gorgonia acerosa I 



Gorgonia acerosa I 



No Gorgonians. 



Gorgonia flabellum 2 



Plexaura flexuosa 3 



Pseudoplexaura crassa 5 



Eunecia crassa 7 



Gorgonia acerosa 6 



flabellum 2 



Pseudoplexaura crassa 2 



Plexaurella dichotoma 2 



No Gorgonians. 



Gorgonia flabellum 4 



acerosa 2 



Plexaura flexuosa 2 



Eunecia rousseaui I 



crassa 4 



Gorgonia flabellum 3 



acerosa 2 



27. 



29. 



'30 



3i- 

 32- 



34- 



35- 

 36. 



37- 

 38- 



39- 

 40. 



41. 



42. 



43- 

 44. 



45 ■ 



Gorgonia flabellum 2 



Gorgonia flabellum 3 



acerosa 1 



Plexaura flexuosa I 



Pseudoplexaura crassa 1 



Eunecia crassa 6 



Gorgonia flabellum 2 



acerosa I 



Plexaurella dichotoma 2 



Eunecia rousseaui. 1 



Gorgonia flabellum 2 



acerosa 1 



Other forms 4 



Gorgonia flabellum 2 



Gorgonia acerosa 2 



Other forms 4 



Gorgonia flabellum 2 



acerosa .' I 



Other forms 3 



Other forms 5 



Gorgonia acerosa I 



Gorgonia acerosa I 



Other forms 3 



Other forms 2 



Gorgonia acerosa 3 



Other forms 2 



Gorgonia flabellum 3 



Gorgonia flabellum 2 



Other forms 4 



No Gorgonians. 



Gorgonia acerosa I 



Other forms 3 



No Gorgonians. 



Gorgonia flabellum 2 



Gorgonia flabellum I 



acerosa 1 



'Beyond this point the depth of the water was too great to allow of the certain identification of any of the 

 gorgonians except Gorgonia flabellum and G. acerosa. The number of individuals of all other species is therefore 

 given under the caption "other forms." 



