134 REPORTS ON INVESTIGATIONS AND PROJECTS. 



part of the sexual products were given off during the interval between Au- 

 gust 21 and 28. During the present season no ripe eggs have been secured 

 up to August 29, and the apparent condition of the gonads is in no way 

 different from that prevailing during late July and early August of last year. 



Investigations on Echinoderms at Montego Bay, by H. L. Clark, of 



Harvard University. 



While enjoying the privileges of the laboratory of the Carnegie Institu- 

 tion of Washington at Montego Bay, Jamaica, in February and March, 191 2, 

 I carried on investigations along three different lines, material being col- 

 lected in each case for further study. 



The most important work was on the post-larval development of brittle- 

 stars (Ophiuroidea), knowledge of which is greatly needed for use in clear- 

 ing up the phylogenetic history of the group. Of one species (Ophiactis 

 savignyi) material was obtained in abundance, the adult brittle-stars and 

 their young occurring in large numbers in the cavities of a red sponge which 

 grows on mangrove roots at the Bogue Islands. While this is a common 

 and well-known ophiuran, nothing has hitherto been published about its de- 

 velopment. After the early larval stages are past and the adult form is 

 assumed, asexual reproduction by fission across the disk occurs more or less 

 repeatedly. As a result specimens with two arms or with three arms, with 

 or without visible rudiments of three additional arms, or with the latter more 

 or less fully developed, are constantly met with, while full-grown specimens 

 have either five or six equal arms. Sufficient material of this interesting 

 species was obtained to make possible the complete working out of its asex- 

 ual reproduction. 



Material was also obtained, though not in such quantity, for the study of 

 the post-larval development of Ophiothrix angulata and of a species of 

 Amphipholis. It was hoped that similar material might be secured for the 

 study of the post-larval development of some holothurian, but no one species 

 was sufficiently common to make the collection of the desired stages possible. 

 On the other hand, a starfish {Linckia guildingii) proved to be unexpectedly 

 common and a considerable amount of interesting material was secured. It 

 has long been known that Linckia can throw off an arm, under proper stimu- 

 lus, and that the arm so severed will develop a new disk with the normal 

 number of rays. But evidence was secured at Montego Bay which seems to 

 show that this is a general and normal method of reproduction in the species 

 and is not dependent on any unusual stimuli or unnatural conditions. 



The echinoderm fauna of the region adjacent to the laboratory was 

 studied as thoroughly as shore-collecting permitted. Satisfactory dredging 

 was not feasible. The reef collecting proved very rich, however, and much 

 interesting material was gathered. In all 57 species of echinoderms were 

 found, of which 10 were starfishes, 13 echini, 16 holothurians, and 18 brittle- 

 stars. Of the starfishes, the most interesting were two exceptionally large 

 specimens of 9-rayed Luidia senegalensis, with disks exceeding 60 mm. in 

 diameter. They were caught on lines set for fish in 30 fathoms and were 

 said to have swallowed both bait and hook. Some very finely colored speci- 

 mens of Stegnaster wesseli, Asterina folium, and Luidia clathrata were pre- 

 served with the retention of most of their natural beauty by being rapidly 

 dried, after killing and hardening in a solution of corrosive sublimate and 

 formalin. Of the echini, the most notable was a species of Schisaster, a 

 genus not hitherto known from Jamaica and previously taken in the West 



