856 



SCIENCE. 



[N. S. Vol. VIII. No. 207. 



Strongylocentrotus was not carefully examined, 

 though at Nahant I have ofteu noted the 

 extrusion of the yellowish, opaque eggs at 

 various times during the warmer months. 



The breeding habits of the star-fish are 

 peculiar. Dr. A. D. Mead has found the 

 breeding period to culminate in Narragau- 

 sett Bay during the last week of June, 

 although at Woods Holl no considerable 

 number reached sexual maturity at any time 

 during the past summer. In 1892 larvEe 

 were abundant on June 18. 



Mr. Caswell Grave paid particular atten- 

 tion to the Ophiurids during the past sum- 

 mer, and was successful in getting many 

 ripe specimens of OphiopJwlis aculeata at 

 ISTahant during the month of June. These 

 he brought to the Laboratory in sea- water, 

 artificially cooled, and they deposited their 

 eggs and sperm between eight and nine 

 o'clock in the evening of the day they were 

 collected. The development was slow, the 

 'pluteus stage' being reached not until 

 three weeks after fertilization, and several 

 of the plutei lived to be thirty- three days 

 old without showing signs of metamorphosis. 

 Mr. Grave followed the development of the 

 sexual glands of Ophiura oUvacea with great 

 care from the first of June, but the period 

 of sexual maturity was not reached until 

 the second week of July, when a limited 

 quantity of fertilized ova was obtained. 

 The larvae proved to be quite different from 

 those of any previously described Ophiuran. 

 Thy one briar eus and Synapta inJuerens (=: Sy- 

 napta girardii) probably breed during June 

 and July. I think the eggs have never 

 been artificially fertilized. Echinoderm 

 larvse, which may have been brought to 

 Woods Holl by currents, were abundant 

 during the middle of June. Brachiolaria 

 swarmed in Narragansett Bay from the 

 last of June to the middle of July. 



Mollusks. — During the first week of June 

 the young of Mytilus, the ' sand-collars ' 

 of Lunatia, the ' eggs-strings ' of Sycotypus 



and the ' egg-capsules ' of Urosalpinx were 

 noted in Narragansett Bay. During the 

 second week of June, Crepidula, Urosalpinx 

 and several naked Mollusks were found 

 ovipositing. Dr. F. E. Lillie has collected 

 eggs of Pecten from July 10 to August 4. 

 On August 17 the breeding period had 

 passed. According to Dr. Conklin the 

 breeding period of Crepidula fornicata lasts 

 from earljr summer until about August 15. 

 The breeding period of Crepidula p)lana is 

 somewhat later and longer, and newly laid 

 eggs were found September 7. Crepidula 

 convexa lasts through much the same period 

 as C. plana. Dr. Lillie says that the un- 

 segmented ova of Unio eomplanata can be 

 obtained from about the middle of June to 

 the middle of July, those of Anodonta 

 toward the end of July and early in August. 

 The ' Gloohidia' of Unio escape in August 

 and September, and the eggs of Anodonta 

 are carried by the mother through the 

 winter and are extruded in the spring. 



Small squid were taken on the surface 

 from June 20 to the close of the summer. 



The clam, 3Iya arenaria, breeds during 

 June and perhaps earlier. The height of 

 the breeding season of the oyster is during 

 the latter part of July, and the develop- 

 ment is so rapid that the young swim in 

 less than six hours after fertilization. 



Mr. S. E. Williams, who kept a record of 

 the surface forms during the past summer, 

 found 'veligers' abundant on June 12, 

 July 9 and July 19. 



Coelenterates. — Cyanea ardica has been 

 taken with ripe eggs as late as June 3, 

 though by the middle of the month only 

 occasional specimens are seen. The eggs 

 readily fertilize, and the young develop 

 freely in the aquaria. The ' Ephyrse' of 

 Aurelia were taken in the tow on June 15. 

 The Scyphomedusse are not abundant at 

 Woods Holl during mid- summer, an oc- 

 casional Dactylometra or an immature Cyanea 

 being almost the sole representative of the 



