Imcmurrich] notes on SOME CRUSTACEAN FORMS 57 



and in each case differing markedly from the y larva?. The group 

 Apoda is based upon a single species, Proteolepas hivincta, which has 

 never been redescribcd since Darwin gave the first account of an 

 example taken from the mantle chamber of Alepas cornu ta obtained 

 at St. Vincent, W.I. The relative frequency of the y IV larva in 

 Passamaqucddy Bay made it seem possible that if Hansen's view was 

 correct its adult form might be discovered in the mantle chamber of 

 some of the Cirrhiped forms native to that area. No Lepadid forms 

 were available for examination, but a careful search of the mantle 

 cavities of a number of examples of Balanus halatwides and B. halanus 

 was made with, however, entirely negative results. Further search 

 is highly desirable on account of the interesting results that success 

 would probably reveal, and it is hoped that opportunities for further 

 studies of the life-history of such interesting larvœ will not be neglected. 



3 A Type v Larva. 



In one collection there was found a single example of a larva 

 which seems also to belong to a Cirrhipedan form, but the group to 

 which it should be assigned is even more doubtful than in the case of 

 the y larva and it has therefore seemed advisable to follow Hansen's 

 example and speak of it as the v type of larva. Unfortunately it was 

 not possible to study it in all its details owing to its having been lost 

 in an attempt to make a permanent preparation of it. 



It had an oval outline and measured about 0-5 mm in its longest 

 diameter, half this length being occupied by the larva proper while 

 the rest was formed by a carapace-like investment surrounding the 

 larval body (Fig. 11). This carapace formed a broad flange projecting 

 on all sides beyond the larval body and presenting upon both surfaces 

 numerous irregular markings arranged in more or less definite concen- 

 tric bands, so that under a low magnification the flange surface seemed 

 to be concentrically striated. Looked at from the ventral surface, the 

 flange terminated medially in a well-defined border, surrounding a 

 depression in which lay the larval body, and, dorsally, in the region 

 corresponding to the larval body, the carapace was convex and showed 

 none of the markings characteristic of the flange region. The material 

 of which the carapace was composed was colourless and almost 

 perfectly transparent, and except for the markings, homogeneous in 

 texture. The markings did not seem to be due to a sculpturing of the 

 surface, but rather to differences in the refrangibility of the material, 

 and in fig. 11 are shown much more distinct than they were in the 

 actual object. 



After some preliminary study the specimen was stained in car- 

 malum with a view to making a permanent preparation of it. The 



