December 20, 1912] 



SCIENCE 



865 



these two groups the term Unionidse ought to 

 be confined. The Asiatic Parresia and Lamel- 

 lidens are not known to the writer but it 

 would seem that they were derived from a dif- 

 ferent Margaritanoid stock and may form a 

 family by themselves. Omitting these the 

 general grouping adopted by the writer is as 

 follows : 



Superfamily Unionoideae. 



Family Margaritanidse Ortmann, 1910. 

 Family Hyriidje Swainson, 1840 (emend.). 



Subfamily Hyi-iin^ s. s. 

 ? Subfamily Mutelinas Gray, 1847. 

 Family Quadrulid^ Von Ihring, 1901. 



Subfamily Quadrulinse s. s. 



Subfamily Pleurobeminffi Hannibal, 1912. 

 Family Unionidse Swainson, 1840. 



Subfamily Unionidaj s. s. 



Subfamily Anodontinse Swainson, 1840. 

 Family Lampsilidffi Von Ihring, 1901. 



Subfamily Lampsilinae s. s. 



Subfamily Propterinie Hannibal, 1912. 

 Symphynota and Anodonta in the sense 

 used by Ortmann are probably composite gen- 

 era due to an analogous degeneration of the 

 hinge in several allied stocks. " Anodonta " 

 imbecilUs appears to group with 8. compressa 

 in Symphynota though perhaps entitled to 

 subgeneric distinction. S. complanata is 

 rather allied to "Anodonta" cataracta and its 

 subspecies grandis. Neither of these are 

 Anodontas in the true sense of the word, for 

 that group like Unio and Migranaja belongs 

 to the Old World and the west coast of North 

 America. The complanata-cataracta group 

 might take the name Pterosygna Raf. (type 

 Alasmodonta complanata Barnes) if that name 

 is available. A. costata probably belongs here 

 also but seems a rather aberrant member. 



The writer would be inclined to give Carun- 

 culina and Micromya generic rank as distinct 

 from Eurynia. 



Considering the fact that Dr. Ortmann has 

 had to deal with a group in which the nomen- 

 clature of the genera has been very imperfectly 

 worked out and the wealth of nominal species 

 and varieties cbmpared with those which may 

 be ultimately recognized as valid is amazing, 

 he is certainly to be congratulated for the care 

 he has taken in presenting clearly a large mass 



of facts without falling into any serious nom- 

 enclatural pitfalls. 



Harold Hannibal 

 Stanford University, Cal., 

 August 3, 1912 



SOME EEMAEKABLE DISCOVERIES REGARDING A 

 COMMON HOUSEHOLD INSECT 



The literature of the nature-study move- 

 ment abounds in remarkable statements re- 

 garding the morphology, development and 

 biology of bird, beast and fowl, but scientific 

 men have hesitated to discard the older the- 

 ories in favor of unsupported statements from 

 such sources. The public can hardly be ex- 

 pected to be SO suspicious of the publications 

 of the United States Public Health Service 

 and it would seem that some of the many 

 astounding facts recently disclosed regarding 

 the common bed-bug should receive wider cur- 

 rency than is assured by their publication in 

 Public Health Eeports, for November 15, 1912, 

 pp. 1854-1856. 



The early history of this pest is shrouded in 

 mystery, but we are informed that it is not at 

 all improbable that when our arboreal fore- 

 bears forsook tree-top for caves they took this 

 little six-legged pest with them. 



This seems to be more likely beeause the English 

 sparrows and the swallow harbor a very similar 

 species, and not infrequently their nests are 

 crowded with these vermin. 



The biting apparatus of this parasite is quite 

 elaborate, and consists of several parts. In biting, 

 the bug anchors itself to the skin with a couple of 

 hooks called mandibles, and then inserts the max- 

 illffi, which are shaped like two gutters, the con- 

 cave surfaces of which look towards each other. 



Normally it feeds upon human blood, but lack- 

 ing this it will live upon decaying wood or the 

 dust in floor cracks. 



The eggs are somewhat rounded, white objects, 

 and are laid in collections in crevices or other 

 suitable places. In about a week or ten days after 

 they are laid the eggs hatch out as little worms, 

 called larvae; these are yellowish white in color at 

 first but later become almost brown. They feed 

 and go into a resting state, from which they 

 emerge as pupae; they then shed their skins five 

 times and at last become full grown adults. 



