10 
A New Leech 
Summary of the principal differences between Calliobdella lophii 
_ and Ganymedes cratere. 
CALLIOBDELLA LOPHII. GANYAIEDE8 CRATERE. 
Posterior sucker well developed without 
a thickened rim. 
1 caecum. 
Vesiculae seminales present. 
Respiratory vesicles 11 pairs. 
Undifferentiated abdomen. 
Neck of 11 annuli. 
Slight dorsi-ventral flattening. 
No gustatory papilla. 
Vas deferens situated external to (he. on 
the body wall side of) the testes. 
Anterior sucker w'ell developed with a 
thickened rim and o muscular 
bands. 
2 caeca. 
No vesiculae seminales. 
Respiratory vesicles 3 pairs. 
Abdomen divided into: 
(1) a Testis region with 6 aimuli 
to a segment. 
(2) a Caecum region with 1 an¬ 
nulus to a segment. 
Neck reduced to 3 annuli. 
Pronounced dorsi-ventral flattening. 
Gustatory papilla in anal region. 
Vas deferens situated internal to (he. on 
the stomach side of) the testes. 
Generic characters. A leech divided in a very marked manner into 
a short neck, and a very flattened abdomen. Each “ complete” segment 
of the abdomen consists of six annuli, but only the first six are so divided. 
Along the side of the abdomen are three pairs of respiratory vesicles. 
Two caeca. No vesiculae seminales. Blackish-brown star-shaped pig¬ 
ment cells are not present. There is no special development of the 
reproductive system. 
Specific characters. It is difficult in a hitherto unknown animal to 
decide which characters are generic and which specific. The following 
points are probably of only specific value: host, Callionymus lyra{1). 
Anterior sucker over fo;ir times the size of the posterior with a muscular 
rim and flve muscular bands. The last segment of the anal region 
bears ventrally a sensory papilla. No eyes^. 
I am indebted to Messrs T. J. Evans and T. Reed of Guy’s Hospital 
Medical School for affording me facilities for my investigations; to 
C. C. L. for sending me the leech; to Mr J. T. Cunningham of the 
South-Western Polytechnic, Chelsea, London, S.W., for his ever kind 
and valuable help; and to Mr Harold R. Southam for reproducing the 
drawings from my rough sketches. 
^ I now consider the presence or absence of eyes of specific and not of generic value as 
in my previous paper {loc. cit.). Thus we have in the genus Platybdella, P. quadrioculaia 
with four eyes and P. anarrhichae without eyes; and others. 
