Tasmanian Temnocephalidea

W. A. Haswell has described from Tasmania three species of Temnocephala, namely, T. quadricornis, T. tasmanica and T. aurantiaca. The descriptions are very brief. In the present paper they have been amplified. In addition three new species, T. cita and T. tulva from Parastacoides tasmanicus· (Erichson) and T. pygmaea from A.stacopsis gouldi (Clark), are described. Observations on the eggs, period of incubation, rate of growth and survival apart from the hosts are given. At ordinary temperatures the eggs of T. cita hatch in 67 days, T. tasmanica in 35-70 days, T. quadricornis in more than 196 days, T. pygmaea in 31-32 days, T. aurantiaca in more than 56 days and T. tulva in mme than 60 days. The times taken to reach adult size by those speci-es, which were hatched in che laboratory and reared apart from their hosts. are as follows: T. tasmanica 233 days, T. pygmaea 152 days and T. aurantiaca 117 days. In the case of T. quadricornis the rate of growth is such that adult size should be attained in about 190 days.
Most of the species, when removed from the host and kept under laboratory conditions, exhibit marked powers of survival. Thus specimenc of T. tasmanica have lived for 707 days, T. quadricornis 76 days, T. pygmaea 59 days, T. aurantiaca 245 days. Young specimens hatched in the laboratory adapt themselves to the conditions more readily and often survive much longer than those removed from the host. Even in the absence of adequate aeration and food some species survive for lengthy periods. Thus, for example, an adult specimen of T. tasmanica placed in 3.0 ml. of water in a small tube, which was .then firmly corked, lived for 100 days. T. aurantiaca treated in the same way lived for 70 days. During the period the animals decreased from adult size to that of a newly hatched specimen.