摘要："There are two species of Siren widely distributed throughout United States. These are distinguished by size at ovulation, the average number of costal grooves, the size of the eggs, thickness of the egg-capsules, the coloration of the young for nine months after hatching, and the body proportions for a more extended period. 2. LeConte did not distinguish between these species when describing Siren intermedia, but we reinstate this name usually placed in the synonymy of lacertina and restrict it to the smaller species described here. 3. The recently hatched young of S. intermedia is remarkable for its long body, short tail, and broad dorsal fin extending the full length of the back. 4. Changes taking place in the head and forelimbs during the first fifty-five days after hatching are described. No balancer ever appears. 5. Reduction of the dorsal fin begins about two months after hatching but is not complete in some specimens until nine months. 6. Both species of Siren are nocturnal. The adult intermedia devours quantities of Spirogyra and possibly other algae with its animal food which consists of crayfish and molluscs"--P. 16.
