56 Records of the Indian Museum. [Vol. XXIV, 



In a vertical section of the striated skin covering the under 

 surface of the pectoral spine of G.saisii (fig. 19, a) the structure 

 in all essential points corresponds to that of the previous examples. 

 The spines (s) are hooked and more regular ; their nuclei (n.s.) are 

 situated near the base and each of them is surrounded by a 

 whitish halo. The nuclei project into the non-cellular region 

 (n.c.r.). Underneath the non-cellular region there are two rows of 

 cavities or open spaces. The cavities of the first row (c') are 

 greatly elongated ; they are broader near the upper than near the 

 lower end. On focussing, a part of the cavity is found .to contain 

 a lightly stained protoplasmic substance. The second row of spaces 

 (c") is similar to the first, but here the lower portion of the cavity is 

 filled with protoplasm ; the upper margin of each cavity is deeply 

 stained and in the section there appears an interrupted band. 

 Then follow large columnar cells (c.e.) which are provided with 

 big nuclei. The nuclei are oval and possess a well-defined nu- 

 cleolus; they are surrounded by a whitish halo. Below these 

 there are several rows of small, rounded epithelial cells, some of 

 which are devoid of any nuclear substance. The basal layer (b.c.) 

 is represented by finger-like processes of protoplasm which do not 

 possess any nuclei. It may be pointed out for the sake of clear 

 understanding that the whole of the structure is one continuous 

 mass and that the cell-boundaries are nowhere marked, but 

 in drawing up the description it has been convenient to treat 

 the structure as if it were composed of a number of distinct 

 layers. 



It is interesting to note the changes in the structure as we 

 pass from the ridge to the grooved portion of the striated skin. 

 Attention may be drawn to the following points of difference in 

 the grooved area (fig. 196) : — 



(i) The spines become smaller and smaller till they are repre- 

 sented by small knob-like projections on the surface. In the 

 middle of the groove the surface becomes entirely smooth. 



(ii) The nuclei of the spines recede inwards and ultimately 

 form a continuous layer just below the surface of the skin. 



(iii) The first layer of cavities is represented by small, oval 

 or rounded spaces in the grooved region. In some cases this la3 7 er 

 may be totally absent. 



(iv) The second row of spaces is represented by small cavi- 

 ties; they are provided with a deeply staining upper margin. 



The structure, on the whole, appears as a mass of proto- 

 plasm in which the nuclei are. scattered either near the base or near 

 the apex and a few cavities are present in the middle. The basal 

 epithelium is represented by finger-like processes as described 

 above. 



In a horizontal section (fig. 19c) the structure of the adhe- 

 sive tissue does not differ greatly from that seen in a vertical sec- 

 tion. The chief difference lies in the form and extent of the various 

 elements noted above. The non-cellular region is separated from 

 the underlying tissue by a regular wavy line of demarcation. The 



