1902.] NATURAL SCIENCES OF PHILADELPUIA. 751 



Woods Hole summer after summer for a number of years, Go7ii- 

 onema was uever found in the Atlantic Ocean until 1894. During 

 that summer a number of specimens were taken from the eel-pond, 

 the creature having made an astonishingly sudden appearance upou 

 the scene. It seems incredible that Gonionema could have been 

 living in this small body of ^yater for any time previously, or at 

 any rate that any number of individuals had been there. ]3ut the 

 jelly-fish at once secured a good " foothold," and since the firet 

 summer it has been very plentiful ; its numbers remain undimin- 

 ished by the wholesale raids of collectors, in spite of the keen 

 anxiety of some of those interested in it. During the sunnner of 

 1894, when Gonionema was first found at Woods Hole, Prof. W. 

 K. Brooks secured a number of specimens and made drawings 

 both from live medusae and from sections of preserved material. 

 Some of these drawings, PI. XXXHI, figs. 21, 22, PI. XXXIV, 

 fig. 25, are now published, with Dr. Brooks' generous permission, 

 foi- the first time. 



The first printed account of the Woods Hole species of Goni- 

 onema, since recognized as distinct from the G. vertens of Agassiz, 

 was published in 1895 by Dr. L. Murbach.^ In several instances 

 the species has been mentioned as identical with G. vertens, and it 

 was not until 1901 that the specific name Murhachii was bestowed 

 upon it by Dr. A. G. JNIayer. 



The work which I have done on the life-hisloiy of this form was 

 originally undertaken and nas since been prosecuted with Dr. Mur- 

 bach's kind encouragement, and I have received from him many 

 favors in the way of material and helpful suggestions. The 

 research has been carried on during 1900 and 1901 at the 

 U. S. Fish Commission Laboratory, where I have had the great 

 privilege of working during the summer, and under the direction 

 of Prof. W. K. Brooks at the Biological Laboratory of the Johns 

 Plopkins University. I wish to acknowledge my obligations to 

 Dr. Bumpus, Dr. H. M. Smith and Dr. Whitman for courtesies 

 wliich they have extended to me in my work. 



Note on the Ontogeny of the " Trachomedus.e. " 



According to Ilaeckel's classification Gonionema falls into his 

 third order, the " Trachomedusse. " Haeckel characterized this 



^ L. MuRBACU, 1895, " Preliminary Note on the Life-History of Gonio- 

 nemus," Journal of irorphology, Xt, 3. 



