December 16, 1898.] 



SCIENGR 



857 



group. At New Bedford, and in Narragan- 

 sett Bay, Dactylometra is excessively abun- 

 dant, and one would probably have little 

 difficulty in getting material for embryolog- 

 ical study at almost any time. Metridium 

 has frequently been seen to extrude its 

 eggs, which may be artificially fertilized, 

 and Sagartia has also been found breeding 

 during the middle of July. 



I am indebted to Professor W. C. Har- 

 gitt for man}' of the following notes on the 

 breeding of Hydroids : 



Clava le-ptostyla.- — Colonies are occasionally 

 taken from rock- weed in the ' Hole, ' from 

 June 18 to the end of the month, and 

 less frequently throughout the summer. 

 Colonies may also be taken from exposed 

 timbers under the wharf of the U. S. Fish 

 Commission. The male colonies are much 

 more abundant and conspicuous. 



Clyiia bicophora, on the shells of Mytiliis, 

 with colonies of Eudendrium, is abundant 

 late in June, when it is in a thrifty condi- 

 tion, and with mature gonangia. 



Eudendrium. — Colonies of Eudendrium, 

 probably E. rcmiosum, were taken in very 

 imperfect condition June 17, apparently 

 just beginning development from old stolons. 

 Specimens were also taken from under the 

 culvert at the outlet of the Eel Pond, on 

 June 20, in a more vigorous condition, 

 but with onlj' male gonophores, which con- 

 tained ripe spermatozoa. Colonies devel- 

 oped rapidly during the following ten days 

 and produced female gonophores. The 

 earliest signs of development of eggs oc- 

 curred during the first week of July. The 

 latest were recorded by Dr. Murbach, on 

 September 15. 



Corynitis Agassizii. — Specimens taken from 

 the wharves of the Fish Commission on 

 June 20, on shells of Mytilus, were in a 

 thrifty condition and bore mature medusae. 

 These are set free during the early evening, 

 and swim actively about the aquarium, 

 though at this time there are no indications 



of sexual products. Several colonies of 

 this interesting H3'"droid were taken, but 

 always from the encrusting deposit of a 

 Bryozoon, which frequently occurs on the 

 shells of Mytilus. 



Hydraatinia (Echinata) polyelina. — Colo- 

 nies taken from the shells of Eupagurids, 

 from rock-weed and from Limulus, were 

 mostly sterile in June, or with only male 

 gonads. It breeds during July and Au- 

 gust. 



Margelis carolinensis is quite common and 

 in an excellent state of growth during June, 

 though without medusa- buds. It is found 

 on the timbers of the Fish Commission 

 docks, on rock-weed and occasionally upon 

 eel-grass. It breeds during August. 



Ohelia sp. — A species of Obelia is very 

 abundant along the rock work and wharves, 

 and during June develops apparently ripe 

 gonangia, though few free medus£e. 



Parypha croeea. — In splendid profusion 

 and perfection throughout the month of 

 June. 



Pennaria tiarella. — During the month of 

 June this species is to be found in limited 

 numbers attached to rock-weed and to the 

 piles of the wharves. Its development is 

 slow, specimens with medusa-buds not being 

 taken until June 29. During the follow- 

 ing weeks the development is more rapid, 

 both of the polyp- stock and of the medusse. 

 Dr. Murbach has found the species breed- 

 ing as late as September. 



Sertularia sp. — Everywhere in abundance, 

 but with gonangia only in a few cases. 

 Several species are found, of which the 

 commoner are Pumila and Argentea. 



Dr. McMurrich found Laomedea amphora, 

 on Fucus, with ripe gonophores, June 2, 

 and associated with it was Halecium, in a 

 similar sexual condition. During the lat- 

 ter part of June and throughout the sum- 

 mer the medusje of Gonionemus is found in 

 great quantities in the Eel Pond. Mr. 

 Williams noted Clytia and Lizzia in the sur- 



