? Y. “3° is > . 
Cysticercus from a rare Dolphin. 423 
As regards the dimensions of the scolex, the present form 
seems to approach most closely to M. elegans, which has 
been fairly fully described by both Zschokke * (1889) and 
de Beauchamp (1905). The length of the scolex in this 
form is given by Zschokke as 0°-4 mm.—0°8 mm., the width 
of the scolex as 0°3 mm.—0°4 mm., and the width of the neck 
as Q°l mm.—0:25 mm. “The other measurements given by 
both authors agree fairly well with those given above for 
the cysticercus. 
There has been some confusion between M, perfectum 
(van Beneden) and M. elegans, but on comparing the original 
descriptions it seems highly probable, as Monticelli (1890 
p- 434, footnote) and de Beauchamp (1905) contend, that the 
two forms are distinct. J. elegans, according to de Beau- 
champ, is 17 or 18 em. in length, while ML. perfectum reaches 
30 to 40 cm, (van Beneden, 1853, 1861) or 12 to 15 inches 
(Diesing, 1863). The scolex is also very much larger in 
M. perfectum, measuring, according to van Beneden, 1-2 mm. 
in width, while Diesing gives it as 2-1", M. perfectum 
would appear tierefore to be a considerably larger form 
altogether than ML, elegans. 
Lire-History. 
It would have been extremely interesting if the eysticercus 
under discussion could have been shown to belong to Mono- 
rygma perfectum, since, as Dr. 8. F, Harmer informs me, the 
host of this species, the Greenland shark (Lemargus borealis) 
has the habit of biting out pieces of the flesh of living 
Cetacea, and this would have afforded a satisfying account of 
the life-history of the parasite. If I. elegans and M. per- 
jectum were shown to be identical, greater plausibility might 
be lent to this hypothesis. For the present, however, it 
seems impossible to assign the cysticercus definitely to any 
of the species. It may very possibly be that of MM. elegans, 
which is parasitic in Scyl/ium spp., and to. which species, as 
has been seen, it approaches closely in the size and structure 
of the scolex. We have also to remember the somewhat 
remarkable fact that the cysticerci can remain alive for at 
least eleven days after the death of the host, and even after 
its removal from the water. Hence they may very well be 
swallowed by any species of dogfish that devours pieces of 
dead dolphins containing the cysts. 
* Zschokke describes it under the name of M. perfectum, Dies. 
28% 
