244 .EOLIDID^. 



with silvery dots ; tail silrery alcove and below ; a russet line passes 

 back from the base of the anterior tentacles to the first branchial 

 tuft. Tentacles long, about equal, suljulate, the terminal half sil- 

 very. BranchiEe rather stout, gradually enlarging, but suddenly 

 contracted near tip, which is transparent, then an opaque-white zone, 

 then a transparent zone, then another white ring where the branchisB 

 enlarges, so that when viewed at the apex we have an apparently 

 open centre enclosed by a white ring, this by a transparent ring, a,nd 

 outside of all another white ring; granular nucleus varying between 

 light l)rown and chestnut. They are arranged in five or more groups 

 quite remote from each other. Each group is composed of two ap- 

 proximate transverse ranges ; the first group is situated at some 

 distance behind the tentacles, and has eight or ten cirri in each 

 range, which decrease in length from above downwards ; the next 

 two tufts have six in a range, then five. Angles of the foot trian- 

 gular, not much elongated. Length, an inch and a half; breadth, 

 one fourth of an inch. 



Found rather abundantly in September, in Charles River, on tim- 

 bers. Dr. Stimpson found it spawning in October and also in June. 



This animal has also a general resemblance to E. coronata and to 

 E. Bostoniensis in form, size, and color, but has still a well-decided 

 difference in the well-marked interrupted stripe on the l3ack, the 

 form and arrangement of the branchice, and the smooth posterior 

 tentacles. The ova found with them were expelled in a bobbin-like 

 string, which was looped and festooned and then attached in a loofe 

 coil to the timbers, or sometimes left at the surface of the water. 

 These eggs, as well as those of other species, are beautiful objects 

 to oliserve under the microscope. At first the yolk is seen to par- 

 tially divide into halves, then into four, eight, sixteen, and so on, 

 till the whole surface becomes granulated ; then little fine hairs begin 

 to appear and vibrate, and the yolk begins to revolve ; then comes a 

 mouth, stomach, and intestine and two eye-like points, which, how- 

 ever, arc the little grains which constitute the car {otolithes'), and 

 so on until the animal assumes a well defined, symmetrical form 

 and very rapid motions. Some of these, which were laid September 

 27th, were watched in their development. October 6th a few were 

 found to have escaped from the egg ; on the next day about one 

 half had become free and congregated at the surface. The little 

 nautiloid shell, scarcely visible to the naked eye, was thinnest and 

 purest crystal, and minutely decussated near the aperture. The 

 stomach and intestine of the little embryo, and the movements of 



