ORGANIC DEPENDENCE AND DISEASE 
73 
Fig. 60. Two specimens of the Devonian crinoid, Taxocrinus lobatus Hall, with a 
coiled snail (Platyostoma) attached to the dome. Canandaigua Lake, N. Y. 
( b . by courtesy of Mr. Frank Springer.) 
A singular and single instance of similar concurrence has 
been found in the Portage Upper Devonian (West Hill 
shales) of Naples, N. Y., a baby Melocrinus, not above one- 
half inch in length (calyx) to which is attached a baby 
Platyceras of about the same size. This is a convincing 
evidence of the early age at which this adaptation became 
effective, though it is no proof that the conjunction may not 
have been broken in later life. It 
is certainly extraordinary that this 
parasitized young condition is the 
only one recorded in these rocks, 
while Melocrinus is the only abun- 
dant crinoid in the Lower Portage 
fauna. 
The Devonian faunas, in these 
cited instances, have thus furnished 
us with instances of the growing 
habit of this parasitic attachment. 
We find it to be occasional and spo- 
radic, desperate and often ill-ad- 
justed arrangements which seem to 
have brought disaster to the hosts. 
We see cases, as Melocrinus mic- 
Fig. 61. Young Melocrinus 
with young snail attached. 
Upper Devonian. 
