64 



•aquatic JLttt 



angles to it and usually at a relatively 

 short distance apart. The present speci- 

 men on the contrary does not possess 

 this arrangement. Both ani are on the 

 median line and are 48 millimeters apart. 

 The posterior anus is located at the place 

 where the normal anus should perforate 

 the body wall, but it is peculiar in that 

 it is the non-functional one of the two. 

 The anterior anus, although 48 milli- 

 meters out of its normal position, is the 

 functional one. The posterior anus has 

 a strip of intestine leading inward which 

 ends blindly about 4 centimeters within 

 the body cavity. It is smaller in diameter 

 than the functional intestine and practi- 

 cally without a lumen. The functional 

 intestine, leading to the anterior anus, is 

 somewhat shorter than that in a normal 

 perch. 



No attempt will be made to explain 

 how this peculiar structure developed, as 

 a competent pathologist and an embry- 

 ologist declined to commit themselves. 



The Diatomaceae of Philadelphia and 

 Vicinity, by Charles S. Boyer, is a de- 

 scription of the diatoms of the region 

 within a radius of one hundred miles, 

 including the forms found in the blue 

 clay of the ancient Delaware River bed, 

 which underlies a portion of the city. 

 The work is profusely illustrated with 

 forty plates, containing more than seven 

 hundred drawings by the author. All the 

 species recorded from the region, includ- 

 ing freshwater, brackish and marine 

 forms, are shown. 



Air. Boyer's work removes the multi- 

 tude of difficulties that have heretofore 

 beset the microscopist who would study 

 the forms of the Middle Atlantic States. 

 The literature of the subject is scattered 

 through the journals of science over 

 many years; major works are rare and 

 expensive and none so satisfactorily il- 



lustrated. The characters distinguishing 

 species of diatoms are often so subtle 

 that no amount of word painting can 

 convey the proper conception, and it is 

 only when a description is supplemented 

 by an adequate drawing that a form can 

 be identified with certainty. And if this 

 opinion is correct, Mr. Boyer has left 

 little to be desired. 



The microscopist who passes the dia- 

 toms neglects the plants that play a not 

 often sufficiently emphasized part in the 

 economy of nature. Before the warmth 

 of spring has awakened the higher 

 plants, the diatoms are abroad, multiply- 

 ing, liberating oxygen in the process of 

 photosynthesis, and preparing the waters 

 for the coming wave of animal life. How 

 great a factor they have been in past 

 ages is evidenced by vast fossil deposits 

 in all parts of the world. Nor is their 

 role in the aquarium to be overlooked. 

 The brown film on the glass is macro- 

 scopic proof of the presence of untold 

 numbers. In the absence of the higher 

 plants the burden of breaking up car- 

 bonic acid is thrust upon them. The 

 "practical man" may be interested in the 

 theory, scarcely tenable, however, that 

 this minute plant is responsible for cer- 

 tain oil fields. Each individual at a stage 

 in its life contains a minute globule of 

 oil, and deaths in great numbers as indi- 

 cated by the extent of the deposits, per- 

 mitted it to accumulate. The theory does 

 not seem to hold for several reasons. 

 When the bed was being formed, water 

 covered the area. The valves of the 

 diatom, when death overtakes it, sep- 

 arate. It seems reasonable that the 

 globule of oil would rise to the surface 

 and be dispersed, and as such beds are 

 formed very slowly, the quantity would 

 not be marked. 



It is easier to see through some fat peo- 

 ple than through some thin ones. 



