Miscellaneous, 179 



It is consequently with great pleasure that I am able to figure for 

 the first time a beautiful Mitraria-VikQi larva, which is found in 

 abundance in the cold waters of the Bay of Fundy. This larva does 

 not occur south of Cape Cod, although it is represented in the waters 

 of Massachusetts Bay at Provincetown, Mass. It is different in forin 

 from the European rejiresentative, of which, in truth, considering 

 the part which it has played in discussion of the affinities of larval 

 forms of animals, too little is known. 



My new larva was first taken by means of the drag-net or tow- 

 net in the summer of 1886. I first found it at Frye's Island, New 

 Brunswick, and afterwards it was taken at Grand Manan. The 

 larva occurred in countless multitudes in July, and later decreased 

 in numbers, but was collected far into August. Later than August, 

 however, I have never seen Mitraria in the nets, although it may 

 and probably does last long into the autumn. The following descrip- 

 tion will give an idea of the general contour and structure of the 

 body of my new larva. 



The body (PI. VII. fig. 4) is hat-shaped, with a narrow rim, 

 gelatinous and transparent. When contracted the equatorial rim 

 or belt of the worm is drawn to the body, imparting a spherical form 

 to the animal. 



There are two ciliated regions of the body. One of these is situ- 

 ated at the apex of the larva, forming a small tuft of cilia, shown 

 in fig. 4. The second ciliated region is found on the rim of the 

 larva, forming a belt skirting the outer border. This second region 

 or ciliated belt is conspicuous on account of the masses of reddish 

 pigment shown in the figure. 



Hanging down from the pole of the larva, opposite the apical 

 tuft of cilia, there is a bifid protuberance, from which arise two 

 fan-shaped bundles of provisional sette. These seta) resemble the 

 embryouic sette so common in larval Chaetopods. They can be drawn 

 together or separated, and are always very conspicuous. Above 

 the protuberances from which the spines arise there is a spherical 

 darkly pigmented body easily seen through the walls of the larva. 



Under the apex of the larva there is a thickening of the epiblast 

 which is connected with the marginal belt by means of a fine thread, 

 shown in fig, 4. The apical tuft of cilia rises from this epiblastic 

 thickening. The digestive system of our larva is very simple, and 

 its yellow walls are readily seen through the sides of the body. It 

 consists of a long tubular oesophagus, the inner wall of which is 

 richly ciliated, opening into an elongated stomach, simple and 

 without cilia *. The mouth lies just inside the ciliated rim or 

 belt, and is separated from the stomach by the globular body, at 

 the base of the spine-bearing protuberance on the lower pole of tho 

 larva. 



The larva is, when expanded, from *15 to -2 millim. in diameter. 



Only a single stage in the growth of this larva was found, and 

 consequently its adult form is unknown. 



* No external opening of the stomach through an intestine was ob- 

 served. 



