804 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [86] 



In No. 1, which was lightly distorted under the compressor, the head 

 measured across the top 1.4 m,n and was quite thin, as shown in the 

 sketch (Fig. 2). The dimensions of alcoholic specimens differ but little 

 from those of the living specimens. 



Although in this species the bothria, being represented by the undi- 

 vided posterior disk of the head, are strictly one, the occurrence of four 

 definite auxiliary acetabula on the margins of the bothrial disk shows 

 its relationship to the family Tetraphyllidce. The auterior plate or disk 

 is probably to be regarded as homologous to the myzorhyuchus of 

 Echeneibothrium. 



Although the head of Lecanicephalum peltatum, as a whole, is some- 

 what suggestive of Van Beneden's figure of Discobothriumfallaoc, the 

 differences are also very profound. Indeed, the figure of D.fallax sug- 

 gests some of the forms of Echeneibotlirium variabiles especially one fig- 

 ured by Olsson (Lunds. Univ. Arssk., Vol. in, Plate I, Fig. 15). 



Anatomy of posterior segments. — Two posterior segments were stained 

 with luematoxylon and cut into longitudinal sections. They furnished 

 the following data: The segments were about .7 mm in length and .2I mm 

 in breadth. The body wall is composed of two layers. The outer of 

 these is a musculo cuticular layer, which is characterized by having a 

 transversely crackled appearance ; the broken lines which produce this 

 effect are about .01 mm apart. The inner layer of the body wall is coarsely 

 granular, the granules being very irregular in shape. 



The genital aperture is marginal, and in a section measuring .7 mm in 

 length was exactly .3 mm from the anterior end. Under a low magnify- 

 ing power the genital aperture appears to lead directly into a some- 

 what pyriform clear space, which is .16 mm long and .08 mm broad, and is 

 directed towards the anterior end at a sharp angle. Its anterior ex- 

 tremity was, in one case, only .16 mm from the anterior end of the segment. 

 When the sections are examined under a magnifying power of from 

 250 to 300 diameters, the appearance of this apparent cirrus bulb is very 

 remarkable. It is then seen to be lined with a dense coat of very fine 

 bristle like spines, which point towards the external aperture. The true 

 nature of this bulb is thus revealed. It is in fact the base of the cirrus 

 itself, and lies in a larger cavity, which also contains additional coils 

 of the cirrus. The walls of the true cirrus bulb appear to be thin aud 

 weak in proportion to the size of the organ to be evaginated. The 

 diameter of a section of one of the folds of the cirrus lying beside the 

 enlarged base was .02 mm . The shape and appearance of the cirrus when 

 extruded must be very remarkable. It is evidently quite long. The 

 spines with which it is beset are quite slender and bristle-like, and 

 measure .006 mm in length. The true cirrus bulb is .19 mm in length and 

 .ll mm in breadth. It lies nearest that margin on which is the genital 

 aperture, and in one of the sections extends to within .14 mm of the an- 

 terior end of the segment. The same measurement was obtained from 

 one of the segments in which the invaginated cirrus appeared in the 

 shape of a loop. 



