From the Translator’s Preface to Invertebrate Spain:

The first three essays herein presented were taken from the volume whose Spanish title, España Invertebrada, provided the subject as well as the title for this book. The others were chosen from other volumes of Señor Ortega’s work because they shed added light on problems which he indicated in that famous analysis, or because they were pertinent to aspects of the present struggle.

The only translation available, then, is not a full translation of España Invertebrada.