NOTES ON PARATYLENCHUS, A GENUS OF NEMAS 



BY N. A. COBB 



Contributions to a Si ience of Nematology, XIV. 



The following paragraphs contain new information with regard to 

 the lip region, vestibule, spear guide, structure of the spear, median 

 oesophageal bulb, salivary glands, deirids (cervical papillae), renette, 

 eggs and their deposition, and gonism of Paratylenchus Micoletsky. 



. - . fl 



Paratylenchus nanus n. sp. 3.7 4.3 / 4,j 4.2 2. The trans- 



parent, colorless, naked cuticle, about 1.5 microns thick, is traversed by plain, 

 transverse striae, 2.0 microns apart except near the extremities, all alike and 

 fairly easy of resolution, which are materially altered on the lateral fields by 

 the presence of wing regions, about one-seventh as wide as the body, beginning 

 on the neck and ending on the tail. The optical expression of the wings on 

 living specimens usually consists in four parallel longitudinal lines on each 

 lateral field, the two outer of which are fainter than the two inner. Very 

 slightly oblique longitudinal striae of the subcuticle, all alike, due to the 

 attachment of the musculature, are rather easily to be seen in nearly all regions 

 of the body. The contour of the body is crenate or very faintly serrate- 

 crenate. There are no dermal appendages and there are no series of pores to 

 be seen in the cuticle. On the neck opposite the excretory pore, lat. 22.2,* 

 there is a papilla on each lateral line, and, leading inward, ventrad and slightly 

 backward from the middle of each papilla is an obscurely sinuous element 

 connecting with the nervous system. These organs are believed to be deirids. 



The neck, which is cylindroid posteriorly, and to a considerable extent also 

 anteriorly, becomes decidedly convex-conoid farther forward, and ends in a 

 rounded or subtruncate, continuous head compassing about thirty annules 

 of the cuticle, which presents a somewhat depressed, very minute, central 

 mouth opening, closely surrounded by six equal, exceedingly minute lips. The 

 truncation of the head occurs at the lip region, which has at this point, that is 

 at the anterior extremity of the nema, a width of about two microns. The lip 



* The Word "Latitude" in Descriptive Nematology. I have lately come to use the 

 word "latitude" in a conventional sense in dealing with nema anatomy, and find it so 

 useful as to lead to this attempt more accurately to define the word as thus used. 



The meaning of latitude in this connection arises from geographical usage, but in 

 nematology the term applies to a transverse plane or section of the organism, and not to 

 a circle on the surface only, as in geography, and it has not seemed desirable to have two 

 sorts of latitude, such as north and south. 



One hundred degrees of latitude is assumed, with zero at the anterior extremity of 

 the organism. Thus an element of the organism in latitude 50 would be at the middle; 

 and in latitude 100 at the end of the tail. The terms can be abbreviated. Thus: lat. 60. 



In the case of nemas, which are so nearly round in cross section, a similar use of the 

 word "longitude" sometimes becomes useful, the ventral line being taken as zero. 



The conventional use of the words latitude and longitude in this way is more or less 

 "logical", and very easily acquired, and, according to my experience, is a decided saving 

 in time and space, and has the merit of definiteness, as well as brevity. 



