372 



SCIENCE. 



[N. S. Vol. XII. No. 297. 



country. They occur in the body-cavity of 

 copepods and also free-swimming in the 

 plankton. 



Three species of Trematodes have been 

 observed on the gills of Fundulus heterocli- 

 tus. Two of them are minute monogenetic 

 Trematodes belonging to the genera Tetra- 

 onohus and Gyrodaotylus which have not be- 

 fore been observed in North America. The 

 species of Tetraonchus is undoubtedly a new 

 one. It is found attached to the gills, 

 from one to three individuals usually occur- 

 ring on each fish. The species of Gyro- 

 dactylus was rare, but four individuals 

 being found during five weeks on the 

 large number of fishes examined. The 

 species is probably new although it may 

 prove to be identical with G. Groenlandicus 

 Levinsen. 



In addition to these monogenetic Tre- 

 matodes large numbers of an encysted 

 distomid worm belonging to the genus 

 Echinostomum were also found. The cysts 

 are oval in shape, each containing a single 

 worm. These were found in all stages of 

 development, the largest showing the two 

 suckers, the digestive and excretory tracts, 

 and the characteristic oral spines. In quite 

 small fishes the cysts were either absent or 

 contained very young worms, and numerous 

 minute ciliated organisms, which were prob- 

 ably the miracidia of Echinostomum were 

 found swimming rapidly over the surface 

 of the gills or lying closely applied to 

 them. 



Development of Squilla Empusa: By Db. C. 



P. SiGEEFOOS. 



This interesting form has been found in 

 great numbers and is apparently much 

 more abundant than usual. It lives at low 

 tide mark in muddy sand to soft mud, in 

 burrows one to four feet or more in length 

 and open at both ends. Observations on 

 the development are in progress. The eggs, 

 very numerous and less than a millimeter 



in diameter, are cemented into a large plate, 

 which is rolled into a bunch and carried in 

 a basket formed by the anterior thoracic 

 appendages. The incubation seems to be 

 slow, and the larvse are about all hatched 

 before August 1st. The new-hatched larva 

 is two and a half millimeters long and of 

 much more advanced organization than in 

 the forms described by Clans. It moults 

 in three days. The later stages have been 

 taken in the tow-net and at this writing 

 (August 11th), are seven millimeters long 

 and in perhaps the sixth or seventh stage. 

 The smallest adults found are over ten 

 centimeters long indicating that this size is 

 attained in one year. 



Variations in Color piattern producedhy Changes 

 in Temperature and Moisture: By W. L. 



To WEE. 



The relations which exist between the 

 variations of the color pattern, moisture 

 and temperature conditions have been tested 

 experimentally during the last two years in 

 Leptinotarsa deeemlineata Say, the Colo- 

 rado potato beetle. Extremely abnormal 

 conditions were avoided and only such devi- 

 ations from the normal were used as might 

 be encountered in different parts of North 

 America. In several series of experiments 

 known deviations of temperature and moist- 

 ure were used and the results derived by 

 quantitative methods. 



The series of experiments show that a de- 

 viation above the normal ( + ) of either tem- 

 perature or moisture, or both, up to a certain 

 critical maximum, will produce melanism ; 

 but a deviation of either factor beyond this 

 maximum will produce albinism. A devia- 

 tion below the normal ( — ) produces albi- 

 nism if both factors are — ; but a + temper- 

 ature and a — humidity produce albinic 

 specimens ; and a — temperature and a -|- 

 humidity produce melanism up to the crit- 

 ical point where the opposite color vari- 

 ations begin to predominate. 



