498 



PSYCHE. 



[August 1893. 



rate knob-like projections. According 

 to Schindler,* Locusta viridissima has 

 more than 100 vessels; "sie munden 

 zwar bei L. viridissima einzeln in den 

 anfangstheil des diinndarms ein, haben 

 sich aber dabei — entsprechend dem fami- 

 liencharakter — deutlich in 4oder 5 ziem- 

 lich umschriebene biischel gruppiert." 

 Schindlerf also studied Decticas verru- 

 civorns. "Die absonderung dieser 

 organe in einzelne (vier) biischel istbei 

 Decticus weniger auffallend, als bei 

 Locusta." I venture to conclude either 

 that Dufour and Schindler have over- 

 looked one or two of the clusters of 

 vessels or, what is more probable, that 

 the forms which they studied presented 

 a fusion of two or more of the primitive 

 clusters. 



Gryllidae. The Malpighian vessels 

 of this group present a very aberrant 

 character ; most, if not all, the forms 

 having in their adult condition a great 

 number of tubules opening into the 

 rectum by means of a single long duct. 

 SchindlerJ estimates the number of 

 vessels in Acheta campestris at about 

 100. 



Rathke§ studied the embryonic con- 

 ditions in Gryllotalpa and found that 

 the embryo leaves the egg with only 

 four vessels, which, even at this time, 

 are connected with the proctodaeum by 

 means of a single duct. Soon another 

 pair of vessels is added, so that we really 

 have a stage with six vessels, albeit 



*l. c. 619. 

 f 1. c. p. 621. 

 X 1. c. p. 616. 



§Zur entwicklungsgeschichte d. maulwurfsgrille. 

 Muller's archiv. 1S44, P- 2 7> ta f- ll > n g- 435- 



united in a single cluster. More vessels 

 are acquired from time to time during 

 larval life, till the imaginal number is 

 completed. 



Oecanthus niveus apparently pre- 

 sents more primitive conditions. Ayers.* 

 who studied the embryology of this 

 insect, makes the following statement. 

 "When the tube (proctodaeum) has 

 elongated so that its enlarged end lies 

 within the fourth or fifth segment of 

 the abdomen (counting from behind 

 forwards) there arises near the free end 

 in the median dorsal line a small 

 trilobed, hollow bud of the ectodermic 

 layer, opening into the lumen of the 

 tube. Each lobe grows rapidly into a 

 small tubular organ, the primitive Mal- 

 pighian vessel. Each of these bifurcates 

 at some distance from the proctodaeum, 

 so that there are ultimately six of the 

 tubes." This account certainly tends 

 to show that in some Gryllids 3 and 2 

 are combined in the primitive number. 

 The common duct seen in Gryllotalpa 

 and Acheta and indicated in the em- 

 bryo Oecanthus may, I believe, be 

 safely regarded as a secondaiy develop- 

 ment, since it occurs in no other group 

 of Orthoptera and but very rarely 

 appears in other orders. 



Acridiidae. The numerous Mal- 

 pighian vessels in this family resemble 

 those of the Locustidae but are not ar- 

 ranged in clusters. In the embryo 

 Mclanophis femur-rubrum I find only 

 six vessels, originating simultaneously 

 in three pairs. 



* On the Development of Oecanthus niveus and its 

 parasite Teleas. Mem. Bost. soc. nat. hist. vol. ili, 

 18S4, p. 246. 



