446 A. E. Verrill — Marine JSlemerUans of New England. 



Addenda to the Enopla, 



I take this opportunity to describe two very remarkable new forms 

 of pelagic nemerteans, of which several specimens were taken by 

 the U. S. Fish Commission Steamer Albatross, in the region of the 

 Gulf Stream. Whether they occurred at the surface or near the 

 bottom I am unable to say, but their form and structure is eminently 

 adapted to a purely pelagic mode of life. In form they somewhat 

 recall Sagltta, though they are much larger and stouter. The in- 

 ternal structure is, however, entirely nemertean, and not very differ- 

 ent from that of the typical Enopla. In that grouj), however, they 

 should form at least a distinct family {Nectonemertidm) . They also 

 have some affinity with Pelagoneniertes^ but differ from that genus 

 widely in form, as well as in having a distinct head and caudal fin, 

 lateral cirriform organs in one species, etc. The latter, moreover, 

 has long, much subdivided intestinal diverticula, which is not the 

 case with our new genera. The resemblance in the structure of the 

 muscular walls of the body and the nervous system is quite marked. 



Several forms occur among the few specimens of Nectonemertidm 

 hitherto obtained. Some of them are entirely destitute of the lat- 

 eral arms or cirri of the neck, which in others ai'e large and long 

 and give them a very striking appearance. But as small specimens 

 of Nectonemertes occur in which the lateral cirri are of small size, 

 it is pi'obable that they would be entirely absent in still smaller 

 specimens of that genus. In the second genus [Hyalonemertea) 

 they are probably never developed. 



Although I have prepared many microscopic sections of two 

 specimens of N'ectonemertes of different ages, I have not yet had 

 suflicient opportunity to work out several important parts of their 

 anatomy, — especially the structure of the brain and certain special 

 organs in the head, supposed to be sensory. But since there is, at 

 this time, no opportunity to illustrate the details of the anatomy, 

 I propose to describe here only the more prominent features, reserv- 

 ing details for another occasion. 



Family, Xectoxemertid.e Verrill. 



Body with highly muscular striated walls, adapted for swimming 

 actively, elongated, more or less flattened, and with a differentiated, 

 muscular caudal fin ; the dorsal and ventral surfaces are similar. 



Proboscis with a distinct bulb and sac. Mouth far forward, close 

 to the proboscis-pore. Intestine straight, with large lateral pouches. 



