844 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [126] 



Of the following measurements, those of No. 1 are of a living speci- 

 men, Nos. 2 and 3 are of alcoholic specimens. 



Dimensions. 



Length 



Breadth of head 



Length of head 



Length of head and neck 



Diameter of neck 



Length of contractile bulbs 



Breadth of contractile bulbs 



Length of first segment, approximate 



Breadth of first segment 



Length of last segment 



Breadth of last segment 



Length of proboscis 



Diameter of proboscis at base 



Diameter of proboscis near apex 



Number of segments 



No. 1. 



mm. 



No. 2. 



mm. 



18.00 



13.00 



0.80 



0.54 



0.46 



0.28 



3.00 



2.20 



0.64 



0.32 



2.00 



1.20 



0.20 



0.10 



0.03 



0.03 



0.30 



0.24 



4.00 



2.40 



0.40 



0.50 



1.60 



1.40 



0.08 



0.08 



0.04 



0. 05 



20 



16 



No. 3. 



mm. 

 14.00 

 0.52 

 0.24 

 2.40 

 0.30 

 1.26 

 0.10 

 0.03 

 0.22 

 2.80 

 0.44 

 1.20 

 0.08 

 0.05 

 16 



In the alcoholic specimens the length of bothrium was 0.28 mm , 

 breadth 0.30 mm . The anterior segments were indistinct. 



The base of each proboscis for a distance of about 0.12 n,ra is 0.08 mm in 

 diameter. At this point there is a sudden offset where the diameter 

 suddenly diminishes to 0.06 mm , thus giving rise to a prominent shoulder 

 which is always on the inner side of the proboscis. The basal part of 

 the proboscis is thickly covered with slender, slightly recurved hooks, 

 which are from 0.005 to 0.010 mm in length and less than 0.002 mm in thick- 

 ness. These hooks are arranged in spirals, the coils of which make 

 rows of hooks almost transverse to the axis of the proboscis. The hooks 

 are longer and straighter near the head than they are at the offset. On 

 the outer side of the proboscis, opposite to and a little way back of the 

 basal shoulder, there is a single large hook. This hook is-broad, recurved 

 and has a strong basal support. Its length is 0.04 mm , breadth at sur- 

 face of proboscis 0.017 mm , breadth of basal support 0.02 l mm . Beyond 

 the basal shoulder the proboscis tapers very gradually to the apex, 

 which in well everted proboscides is about 0.04 nnn in diameter, or one- 

 half the diameter at base. The proboscis in front of the basal shoulder 

 is covered with slender hooks, which are for the most part but slightly 

 recurved. The maximum length of these hooks is about 0.015 mm , breadth 

 at base 0.002 mm . They are arranged in spirals 0.016 nim apart, eight or 

 nine hooks being visible in a single spiral. The coils of the spiral are 

 more rapidly ascending than they are at the base. Towards the apex 

 the hooks grow somewhat smaller. There is a slight difference between 

 the hooks of opposite sides of the proboscis immediately above the basal 

 part. On the outer side — that is, the side which bears the large basal 

 hook — they are small, short, rather stout, sharply recurved, and about 



